non neoplastic liver

SURGICAL PATHOLOGYLiver: Non-neoplastic ConditionsAugust 17, 2010

VIRAL HEPATITISACUTE HEPATITISDefinitionAcute infection by hepatotropic viruses A, B, C, D. The necrosis can be spotty, bridging or submassive.

Clinical features Severe and very severe necrotizing hepatitis:

o uncommono clinically fulminant hepatitis with:

acute liver failure coma

PathogenesisAcute Viral Hepatitis B

Liver cell damage apparently caused by T cell-mediated and humoral mechanisms1

Thought to be an ‘elimination type’ of disease: o i.e. virus eradication ensures self-limited course2

Histopathology Appearance due to different hepatitis viruses may be similar Varying severity:

o mildo moderate:o severeo fatal

Lesions involve: o lobular parenchymao portal tracts

Typical Acute Viral Hepatitis Spotty necrosis Panlobular Changes may predominate in:

o centrilobular region in hepatitis B and Co periportal zone in hepatitis A

Hepatocellular alterations variable Some parenchymal cells:

o show: ballooning (Fig. 1)

Fig. 1: Acute viral hepatitis B. Centrilobular area of liver lobule, characterized by liver cell pleomorphism (including ballooning of hepatocytes), some canalicular bilirubin stasis, focal liver cell loss, and mononuclear (mainly lymphocytic) inflammatory infiltration. (H&E)

increased cell volume pale-staining, granular cytoplasm:

i.e. hydropic changeo probably precursor stages of lytic necrosis or cell

dropout Other hepatocytes:

o show: shrinkage increased eosinophilia nuclear pyknosis

o most represent cells in process of apoptosis3,4o may appear as:

condensed shrunken cell clusters of cell fragments:

may contain pyknotic nuclear material

o often described as: acidophil bodies Councilman bodies (incorrect term)

o may be: naked in close proximity to mononuclear

inflammatory cells (Fig. 2)

Fig. 2: Detail of lobular parenchyma in mild acute viral hepatitis C. Eosinophil condensation of hepatocellular cytoplasm (Mallory body-like) and rounded eosinophil fragments of apoptotic hepatocyte, with a few adjacent mononuclear inflammatory cells. (H&E)

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SURG PATH – Non-neoplastic of 47

inside phagocytosing macrophages Mild steatosis:

o minority of cases Several hepatocytes may appear in mitosis Syncytial, multinucleated, giant hepatocytes:

o typical of neonatal hepatitiso sometimes in adultso without diagnostic significance for specific etiology

Loss of normal regular liver cell plate pattern: o i.e. lobular disarrayo diagnostically helpfulo due to combination of:

heterogeneous appearance of parenchymal cells:

ballooning shrinkage apoptosis

cell dropout regeneration of surviving hepatocytes

Some microscopic bilirubin stasis: o commono reflects variable degree of cholestasis

Inflammatory cells infiltrate altered parenchyma: o predominance of mononuclear and lymphocytic cell

typeso most lymphocytes are activated memory T cells5o also plasma cells from early stage6o small clusters of lymphocytes represent:

foci of cytotoxic lymphocyte-mediated target cell attack

described as: focal inflammation focal necrosis spotty necrosis

Kupffer cells: o enlargeo become more prominento phagocytose cell debris from dying hepatocytes:

results in intracellular accumulation of clumps of golden brown, lipid-rich ‘ceroid’ pigment:

best revealed in PAS–diastase stains

these ‘ceroid macrophages’ are: small and scattered as single

cells in earlier stages larger and form clusters that

predominate in centrilobular and midzonal areas later

found migrated into portal connective tissue in still later stages

may stain for iron in acute viral hepatitis

Acute Viral Hepatitis Lobular parenchymal lesions predominate Portal tracts:

o mononuclear cell infiltration: composed of:

lymphocytes plasma cells neutrophils eosinophils pigment-laden macrophages:

especially in later stages

usually within portal connective tissue, with preservation of limiting plate

sometimes spills out into adjacent parenchyma:

blurs outline of portal tract resembles piecemeal necrosis or

interface hepatitis characteristic of chronic hepatitis

Acute Hepatitis Increase in ductular profiles at portal–parenchymal interface:

o so-called ductular reactiono very mild in classical acute lobular hepatitiso better revealed by cytokeratin 7 immunostainso extent increases with severity of necrotizing

parenchymal lesions May be:

o lymphocytic infiltration between and inside bile duct lining cells

o some bile duct epithelial damage:o especially in viral hepatitis C7

Later Stages Of Acute, Self-Limited Hepatitis Most parenchymal and portal changes gradually disappear Residual changes:

o such as: mild infiltration in some portal tracts some focal inflammation in lobules a few remaining macrophages anisokaryosis too prominent for patient's

ageo may persist for several months

Minimal Acute Hepatitis Limited damage and inflammation Slight liver cell ballooning Some apoptotic bodies No bilirubin stasis Mild lymphocytic infiltrate Scant numbers of macrophages Minimal infiltration in only part of portal areas

Severe Acute Hepatitis Acute hepatitis with bridging necrosis Death of larger groups of hepatocytes More extensive parenchymal damage:

o usually lytic necrosis of hepatocytes affecting contiguous parenchymal territories:

i.e. confluent necrosis predominantly in microcirculatory

periphery Patterns of necrosis best explained according to acinar concept of

liver architecture:8o with increasing severity, confluent necrosis wipes out

parenchyma of periphery of acinar zone 3: results in centrilobular confluent necrosis

o a higher degree involves entire acinar zone 3: results in dropout of parenchyma between

portal tracts and central veins: i.e. bridging hepatic necrosis:

used to have a broader meaning9,10

here definition is: acinar

zone 3







necrosis, or

portal–central bridging necrosis (Fig. 3)

Fig. 3: Severe necrotizing acute viral hepatitis B. Overview of liver lobule; mild to moderate mononuclear cell infiltration in portal tracts (lower left, top, and lower right). Bridging portal–central confluent lytic necrosis, realizing a ‘star-shaped’ area of necrosis with a centrilobular vein at its center and peripheral points reaching portal tracts. Inflammatory cells are scattered throughout the lobule. (H&E)

)o even higher degree of severity;

lytic necrosis of all acinar zones: i.e. panlobular and multilobular

necrosis

Necrotic Bridges Change in appearance over time:

o if new: reveal lobular areas where parenchyma has

disappeared, without or little collapse of reticulin framework

necrotizing areas infiltrated by: mononuclear cells some small ceroid macrophages

o later stages: collapse of reticulin fibers proliferation of mesenchymal cells collagen deposition possibly:

bulging of regenerating remaining parenchyma

larger numbers of ceroid macrophages

o older necrotic bridges: heal with fibrous scars:

result in portal–central bridging fibrosis

o severely necrotizing hepatitis:

more severe periportal ductular reaction areas of surviving parenchyma:

changes of classical lobular hepatitis but:

usually more marked: focal

necrosis bilirubin

stasis

Acute Hepatitis With Panlobular And Multilobular Necrosis Submassive liver necrosis Severe and very severe necrotizing hepatitis Parenchyma:

o lytic confluent necrosis: throughout entire liver lobule:

i.e. panlobular necrosis affects several adjacent lobules:

i.e. multilobular necrosis: if survive results in

alternating: collapse

and fibrous scarring of necrotic zones

nodular regeneration of surviving parenchymal territories

o extensive confluent necrosis usually distributed heterogeneously throughout liver:

needle biopsies may not be representative Ductular reaction:

o more prominent in multilobular necrosiso represents attempt at regeneration by liver progenitor

cellso corresponds to ‘atypical’ ductular reaction:

i.e. epithelial proliferation comprises: bile ductular cells transitional cells with phenotype

intermediate between cholangiocytes and hepatocytes11,12

o if severe necrosis or sepsis: some ductules may contain inspissated

bilirubin-stained concrements:13 should not be mistaken as sign

of biliary obstruction

Special Stains and ImmunohistochemistryAcute Viral Hepatitis A14–17

Immunohistochemistry: o viral antigen in cytoplasm of:

hepatocytes Kupffer cells18

Viral RNA located by in situ hybridization19

DiagnosisAcute Viral Hepatitis

Histology: o similar for acute viral hepatitis A, B, C, D, and Eo may be confused by:









coinfection with more than one virus concomitant liver disease, e.g.:

hepatitis of alcoholic type primary sclerosing cholangitis

Acute Viral Hepatitis A14–17 May be:

o dominant centrilobular bilirubin stasiso little liver cell damage and inflammation

May cause cholestatic hepatitis: o particularly in adultso may be some bile duct damage20

Sometimes hepatitic changes show periportal predominance, with dense, plasma cell-rich portal infiltrates:

o periportal parenchymal necrosis with interruptions of canals of Hering may contribute to the cholestatic features16

Also other patterns of hepatitis Rarely:

o severely necrotizing hepatitis with multilobular necrosis

May be fibrin ring granulomas21,22 Requires serologic analysis:

o occasionally prolonged and polyphasic clinical course with two or more relapses of rise in transaminase values23

Acute Viral Hepatitis B When fully developed:

o little or no hepatitis B surface antigen (HBsAg)o hepatitis B core antigen (HBcAg) demonstrated

immunohistochemicallyAcute Viral Hepatitis B

Similar to other forms of hepatitis14,15,24,25 Centrilobular predominance of liver cell damage and

inflammation Lymphocytes may lie:

o in close contact with hepatocytes: i.e. peripolesis

o inside hepatocytes: i.e. emperipolesis

Ground glass hepatocytes: o not seeno presence indicates chronicity

Intravenous drug abuse recognized by presence of birefringent spicules of talc in portal tracts26,27

Controversial about whether chronic course can be predicted on findings in liver biopsy during acute stage:

o no single lesion has predictive value in early infectiono later biopsies (> 2 months) may yield unfavorable

prognostic information: in form of periportal interface hepatitis28 possibly also confluent lytic (bridging)

necrosis definitely when viral antigens (HBsAg,

HBcAg) can be demonstrated in tissue

Acute Viral Hepatitis C Essentially features previously described for non-A, non-B

hepatitis, i.e.:21,29–31o liver cell swellingo apoptosiso cholestasiso lymphocytic intralobular infiltrationo bile duct damage

o portal lymphoid aggregates and lymphoid follicles: most characteristic features of chronic

hepatitis C Lymphocytic infiltration:

o may be prominent in sinusoids (‘Indian file’ appearance) in absence of noticeable parenchymal damage:

resembling Epstein–Barr virus hepatitis: i.e. mononucleosis-like picture

Steatosis: o fairly common24

Fulminant hepatitis with multilobular necrosis rare in developed countries

Immunohistochemistry in situ hybridization for HCV RNA:32o overall results lack specificity

Acute Viral Hepatitis D Three settings:

o simultaneous acute hepatitis D infection and acute type B hepatitis

o acute hepatitis D superimposed on chronic hepatitis Bo chronic hepatitis D infection superimposed on chronic

hepatitis B33 Histology similar to other forms of hepatitis, but tends to be more

severe: o cannot be reliably distinguished from hepatitis B or

C34–36 Immunohistochemistry for HDV antigens in tissue reliable for

documenting infection34,36,37 Microvesicular change in hepatocytes:

o in parts of South America and Africa38o i.e. spongiocytic change or morula cell degenerationo attributed to accumulation of small lipid droplets in

damaged hepatocytes

Severe Necrotizing Hepatitis Causes:

o hepatitis viruseso autoimmune hepatitiso adverse drug reactionso toxic liver cell necrosiso Wilson's disease

Often impossible to pinpoint etiology on histologic grounds because all or most parenchymal cells disappear through lytic necrosis

Minimal Acute Hepatitis Poorly diagnostic picture:

o resembles nonspecific reactive hepatitis: mild hepatitic changes in liver with

extrahepatic inflammatory disease (e.g. pneumonia)

Differential Diagnosis- Drug Induced Toxic Liver Injury- Steatohepatitis

Acute Viral Hepatitis A14–17 May be mistaken for other causes of cholestasis:

o e.g. drug-induced cholestasis

Acute Hepatitis With Marked Cholestasis Differentiated from obstructive forms of cholestasis by typical

necroinflammatory lobular lesions in acute hepatitis

Drug-induced Hepatitis


















May be indistinguishable histologically from viral hepatitis: Features suggestive of drug-induced lesion:

o sharply delineated centrolobular necrosiso abundant eosinophilso granulomas

Absence of these features does not exclude drug hepatitis

Autoimmune Hepatitis Can have acute onset histologically similar to viral hepatitis

Acute Hepatitis Of Alcoholic Type Recognized by:

o conspicuous steatosiso Mallory bodieso neutrophil satellitosiso pericellular (‘chicken-wire’) fibrosis

Acute vs Chronic Hepatitis Histologic differentiation between acute and chronic hepatitis

difficult To make diagnosis consider:

o global histologic picture: differentiation generally based on:

predominance of: portal and periportal

changes and fibrosis in chronic hepatitis

lobular lesions in acute hepatitis

o clinical data Fibrous bridges in chronic hepatitis recognized by gradual

deposition of elastic fibers: o i.e. positive elastica stains:o bridges in acute hepatitis stain negative

CHRONIC VIRAL HEPATITISDefinitionChronic inflammation of the liver. Common causes include hepatitis B, hepatitis C, autoimmune and cryptogenic.

PathogenesisMultiple EtiologiesViral

HBV HDV HCV1 Combined infections:

o B+Do B+Co C+HIVo C+HGV

Nonhepatitis Viral Causes Cytomegalovirus Epstein–Barr virus Herpes virus Adenovirus

Other Autoimmune2 Drug-induced3,4

Chronic Viral Hepatitis B Successive phases of viral replication, elimination, and integration,

associated successively with:

o lesser, higher, and again decreasing degrees of necroinflammatory disease activity5,6

o implies successive occurrence of CPH and CAH variants in individual patients

Chronic Hepatitis C Hepatocellular damage mainly immune mediated7

Factors Associated With Fibrosis Strength of association varies Include:

o male gendero advanced ageo excessive alcohol useo duration of infectiono HIV coinfection8–10o nonalcoholic steatohepatitis11o porphyria cutanea tarda12

HistopathologyElementary Lesions

Comprise: o spotty necrosiso confluent lytic necrosiso portal inflammationo interface hepatitiso fibrosiso cirrhosis13

Spotty Necrosis An older term Loosely applied to:

o apoptosiso genuine necrosis of single hepatocytes

More appropriate term would be focal necroinflammation: o recognizable as:

small cluster of mononuclear cells: lymphocytes possibly histiocytes

may be adjacent identifiable apoptotic body or bodies

Looks the same as in acute hepatitis (Fig. 1)

Fig. 1: Acute viral hepatitis B. Centrilobular area of liver lobule, characterized by liver cell pleomorphism (including ballooning of hepatocytes), some canalicular bilirubin stasis, focal liver cell loss, and mononuclear (mainly lymphocytic) inflammatory infiltration. (H&E)

Confluent Lytic Necrosis More severe disease14 Dropout of contiguous groups of hepatocytes with denudation of

reticulin framework












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Extent may range from focal and zonal over ‘bridging’ confluent necrosis (Fig. 2)

Fig. 2: Bridging confluent lytic necrosis in severe chronic viral hepatitis B. Inflamed portal tract ‘bridged’ through area of necrosis with centrilobular area (lower left). The upper right part corresponds to an area of extensive lytic necrosis in phase of postnecrotic collapse of the reticulin framework and early fibrosis. (H&E) to more extensive panlobular and multilobular

Often small, glandlike clusters of surviving hepatocytes – hepatitic rosettes – within inflamed tissue (Fig. 3):

Fig. 3: Severe chronic viral hepatitis B. Area of multilobular lytic necrosis in phase of postnecrotic collapse and early fibrosis, with several small islands of surviving hepatocytes, appearing swollen and pale, and sometimes arranged in tubular fashion (‘hepatitic-type liver cell rosettes’). (H&E)

o usually surrounded by connective tissueo presumably attempts at regeneration from surviving

hepatocytes

Portal Inflammation May be:

o mildo moderateo dense

Composed of: o mononuclear cells:

mainly lymphocyteso variable numbers of plasma cellso other mononuclear cells:

histiocytes immature lymphocytes

May be: o lymphoid aggregateso true lymphoid follicles

Interface Hepatitis Originally termed ‘piecemeal necrosis’ (Fig. 4)

Fig. 4: Marked interface hepatitis (‘piecemeal necrosis’) in chronic viral hepatitis B. Note inflamed portal tract (upper right) and wedgelike extension of necroinflammation (towards lower left) and irregular interface between portal periphery and adjacent parenchyma all around the necroinflammatory area.

Interface hepatitis preferred terminology because: o mode of liver cell death is apoptosis, not necrosis15–

17o lesion is at interface between:

mesenchyme (portal tract or septum) parenchyma

Periportal18 Corresponds to extension of lymphocytic portal infiltrate beyond

limits of portal tract Associated with cell death (cell by cell or ‘piecemeal’) of

hepatocytes Surviving hepatocytes trapped within inflammatory infiltrate Neoangiogenesis Fibrosis May be:

o mild: one or a few foci around portal perimeter

without noticeable fibrous extensiono severe:

wedge-shaped extension of necroinflammatory lesion

obvious fibrosis deep into lobule Causes enlargement of portal tracts with irregular outlines

Fibrosis Progressive in more active variants Intralobular fibrosis:

o apparently due to continuous ongoing lobular necroinflammatory damage19

Septal fibrosis: o may be:

periportal: presumably result of interface

hepatitis portal–portal:

presumably result of interface hepatitis

portal–central septa: apparently result of portal–

central (bridging) confluent necrosis

Cirrhosis Result of:

o ongoing necroinflammationo progressive fibrosiso parenchymal regeneration

Necroinflammatory changes may: o subside:












i.e. inactive cirrhosiso continue unabated:

i.e. active cirrhosis

Chronic Viral Hepatitis B Viral antigens may be recognizable by light microscopy, creating

helpful diagnostic markers such as: o ground glass hepatocyteso sanded nuclei

Ground Glass Hepatocytes20 Parenchymal liver cells with:

o finely granular and more pale appearance of part or all cytoplasm – ‘ground glass’ area:

often separated from cell membrane by clear halo – an artefact (Fig. 5)

Fig. 5: Chronic viral hepatitis B, high magnification. Ground glass hepatocytes, characterized by more pale, eosinophilic, and homogeneous cytoplasm than surrounding normal (more granular) hepatocytes. Note (artefactual) cleft between ‘ground glass’ cytoplasm and hepatocellular cell membrane. The first nucleated hepatocyte in the left lower corner reveals a less pronounced ‘ground glass’ appearance (corresponding to less extensive endoplasmic reticulum hyperplasia and less massive accumulation of HBsAg). (H&E)

due to marked hypertrophy of smooth endoplasmic reticulum:

displaces cytoplasmic organelles to periphery of cell

contains excess filamentous structures of HBsAg in cisternae:21,22

HBsAg relationship confirmed by special stains, such as:

Shikata's orcein stain23

Victoria blue24

aldehyde fuchsin25

specific antibody

not entirely specific: occurs in other liver

diseases26–32

Sanded Nuclei Larger central part of nucleus:

o finely granularo pale eosinophilic:33

due to massive accumulation of HbcAg not easily recognized specific immunohistochemistry helpful in

identifying HBcAg

Findings During Course Of Disease Vary

Early Viral Replication And Immune Tolerance Phase Minimal hepatocellular damage and inflammation HbcAg37 and HbeAg in:38

o nucleuso cytoplasmo liver cell membranes (Fig. 6)

Fig. 6: Chronic viral hepatitis B; viral replicative phase. Hepatitis B core antigen is localized in hepatocellular nuclei and, in several hepatocytes; also in the cytoplasm and cell membrane. (Immunoperoxidase stain for HBcAg)

HbsAg in: o cytoplasm of some scattered hepatocyteso membrane of numerous parenchymal cells:

honeycomb-like pattern (Fig. 7)

















Fig. 7: Chronic viral hepatitis B: viral replicative phase. Hepatitis B surface antigen is localized in variable quantity in the cytoplasm and in the cell membrane of several hepatocytes. Note only mild lymphocytic infiltrate in portal tract and lobule. (Immunoperoxidase stain for HBsAg)

Viral Elimination Phase Low viral replication Immune clearance of hepatocytes Seroconversion from HBeAg to HBe antibody Disappearance of HBV DNA from serum More necroinflammatory lesions:

o including confluent lytic necrosis in more severe cases42

HBcAg in: o nucleuso cytoplasmo liver cell membranes

HBeAg in: o nucleuso cytoplasm43

HbsAg: o weak positivity in cytoplasm of some hepatocytes with

membranous staining pattern:34,35,41 mild inflammation may persist for some

time after loss of HBsAg in serum44 After acute exacerbations45 cirrhotic changes in ≈40% of

patients:34o if cirrhosis does not supervene liver may recover with

only minimal histologic abnormalities46 Sometimes ongoing inflammatory activity and interface hepatitis:

o due to persistence of a special mutant of HBV with deficient HBeAg synthesis47,48

o immunostaining reveals cytoplasmic HbcAg49

Phase Of Viral Integration Occurs when some virus-replicating hepatocytes apparently

escape immune elimination: o leads to:

persistence of viral infection integration of viral DNA into host genome:

HBsAg is continuously produced by these cells50

patient becomes HBsAg carrier HBsAg accumulates in clusters of

hepatocytes: appears as:

ground glass cells, or

staining in periphery of parenchymal cells (Fig. 8

Fig. 8: Chronic viral hepatitis B: viral nonreplicative (integration) phase. Hepatitis B surface antigen is localized in considerable quantity in the cytoplasm of a contiguous group (‘clone’) of hepatocytes. Note relatively mild lymphocytic infiltrate in portal tract and lobule. The more intensely staining cells appear as ‘ground glass hepatocytes’ on H&E staining. (Immunoperoxidase stain for HBsAg)

HBcAg usually absent No active replication of HBV More aggressive forms of disease41 and cirrhosis46 more likely if:

o persistent HBcAg in livero higher level of HBV viremia

May be: o normal architectureo variable degrees of fibrosiso cirrhosis:

progresses slowly over 20–30 years eventually decompensation and other

complications initially micronodular later more macronodular34 may be complicating hepatocellular

carcinoma: Healthy HBsAg carriers:

o no cirrhosiso risk for hepatocellular carcinoma

May be precancerous lesions in precirrhotic and cirrhotic stages: o large cell dysplasiao small cell dysplasiao macroregenerative nodules

Chronic Viral Hepatitis B + D Compared with uncomplicated chronic hepatitis B chronic

hepatitis D tends to be: o more severe, with:

higher activity risk of progression51,52

Occasionally: o rapid progression to cirrhosis with active HBV

replication More commonly:

o slow disease evolutiono evolves into cirrhosis over many years53,54

HDV: o selectively suppresses HBcAg and HBeAg, but not

HbsAg55o depends on low-grade HBV multiplication and

release56 Immunohistochemically, HDAg found:

o mainly in liver cell nuclei:57 may show sanded appearance58 due to

excess HDAg























o in cytoplasm and membranes of hepatocytes59 Double immunostaining for HBV and HDV antigens:

o often separate expression of HDAg versus HBsAg or HbcAg

o may be coexpression60

Chronic Viral Hepatitis C 170 million people with chronic infection worldwide61,62 Usually silent onset High rate of viral persistence Potential worsening chronic liver disease:

o chronic hepatitiso cirrhosiso occasionally hepatocellular carcinoma61

Retrospective studies tend to overestimate progression to cirrhosis and cancer

Prospective and cohort studies: o indicate lower rate of progressiono suggest spontaneous viral clearance may be higher

than thoughto severe, life-threatening, progressive liver disease in

perhaps 30% of those chronically infected Characteristic histopathology:63–66

o initially often mild with little parenchymal damage:67,68

o mainly focal inflammation and hepatocellular apoptosis69

o spontaneous exacerbations70o reactivation after immunosuppressive therapy71o relapse after interferon therapyo portal infiltrate rich in lymphocytes:

often lymphoid aggregates (Fig. 9)

Fig. 9: Chronic viral hepatitis C. Low-power view of two joined portal tracts with dense mononuclear cell infiltration, forming a lymphoid aggregate and a lymph follicle. The portal–parenchymal interface is irregular (moderate degree of interface hepatitis). A few scattered macrovesicular steatosis vacuoles are visible in the lobular parenchyma. (H&E)

even follicles: particularly prominent germinal

centers72–79 not specific for hepatitis C also in:

hepatitis B72,77 autoimmune

hepatitis72 primary biliary

cirrhosis Lesions of interlobular bile ducts (Fig. 10):

Fig. 10: Chronic viral hepatitis C. Detail of portal tract showing a lymph follicle containing an irregular and damaged bile duct near its center. Note the epithelial irregularity and intramural lymphocytic infiltrate. (H&E)

o in 15 to 91% of biopsies:65,72

i.e. poor consensus on definition of bile duct lesion

o most frequently observed lesion: infiltration of lymphocytes between

cholangiocytes bile duct lining cells show variable degrees

of: vacuolation stratification crowding

o most pronounced bile duct lesion:80 swelling and polystratification of bile duct

lining cells infiltration by lymphocytes and larger

mononuclear cells preservation of basement membrane81 differentiate from lesion in primary biliary

cirrhosis Lobular lesions:

o may comprise striking number of acidophil bodies (apoptosis)

Mild to moderate steatosis (Fig. 11):

Fig. 11: Chronic viral hepatitis C: moderately dense portal infiltrate, focus of interface hepatitis; marked macro- and mediovesicular steatosis; occasional apoptotic body (middle left). (H&E)

o usually macrovesicularo in 1 to 72%65,72 of biopsieso appears to be mainly viral effect,82 especially of HCV

genotype 383 Periportal hepatocytes:


























o may contain coarse clumps of eosinophilic cytoplasm: Mallory body-like77,84

Lymphocytic infiltration in lobules: o may form rows along sinusoids (Indian files):

resembles hepatic mononucleosis Venous lesions:

o resemble endotheliitis in cellular liver allograft rejection85

Epithelioid granulomas: o in 5% of cases86–88o apparently transient89o has been correlated with interferon-α therapy90o associated with good91 and bad response92o exclude other causes of granulomas87

Some bile duct loss in late (cirrhotic) stage:93o differentiate from primary biliary cirrhosis

Increased hepatic iron: o even in absence of blood transfusion or alcohol

abuse94o iron overload impairs response to interferon

therapy:95 liver biopsy assessment should include

comment about presence or absence of excess iron in hepatocytes96

Similar histopathology in children:97o perhaps faster development of fibrosis98

Different genotypes of HCV may influence histopathology, such as:

o degree of steatosiso rate of bile duct lesionso disease activity99,100

Increased inflammatory activity, especially interface hepatitis:101o if clinical manifestations of autoimmunity

Premalignant Lesions In Chronic Viral Hepatitis B and C Strong association between hepatocellular carcinoma and:

o chronic hepatitis B102o chronic hepatitis C103

Main presumed or proven premalignant lesions in chronic hepatitis type B and C:

o liver cell dysplasia: large and small cell types:104

dysplastic foci: groups of (large-cell

or small-cell) dysplastic hepatocytes <1mm diameter105

o macroregenerative nodules (adenomatous hyperplasia)106

Large Cell Dysplasia107 Hepatocytes:

o enlargedo nuclei:

irregularly shaped hyperchromatic prominent nucleoli

o nucleocytoplasmic ratio: normal or slightly increased108

Mainly HBV and HCV infection109 Not direct forerunners of malignant carcinoma cells An independent risk factor for development of hepatocellular

carcinoma110

Small Cell Dysplasia Hepatocytes:

o smaller than in large cell dysplasiao cytoplasm:

basophilico nucleus:

moderately increased sizeo nucleocytoplasmic ratio:104

increased May be a better precancerous candidate than large cell

dysplasia111

Macroregenerative Nodule Previously termed adenomatous hyperplasia Unusually large regenerative nodule ≥0.8cm diameter In cirrhosis and other chronic liver disease:

o particularly macronodular cirrhosis112,113 Dysplastic nodules:

o >1mmo considered to be more advanced precursor lesions105o low or high grade, with varying degrees of:

liver cell dysplasia increased cellularity loss of cohesiveness pseudoacini focal loss of reticulin fibers113,114

Autoimmune HepatitisHistopathology of chronic hepatitis

Suggestive features:101,115o necroinflammatory activity tends to be high in

untreated patientso common features:

bridging confluent necrosis marked interface hepatitis hepatitic liver cell rosettes116

May be multinucleated giant hepatocytes:117,118o also in other types of hepatitis116

Inflammatory infiltrate: o mainly lymphocyteso prominent plasma cells:

often clusters72o may be lymphoid aggregates and follicles:

less than in viral hepatitis C May be overlap syndrome with features of biliary disease:

o confounded by finding of bile duct lesions in genuine autoimmune hepatitis119

DiagnosisChronic Viral Hepatitis C

HCV RNA detection in frozen liver tissue sections by in situ hybridization:

o lacks specificity120 Immunocytochemical demonstration of viral antigens in

cytoplasm of hepatocytes: o few antibodies give reproducible and clinically useful

results in paraffin-embedded materialo antibody IGH222 (Innogenetics, Ghent, Belgium) may

be more promising (Fig. 12)








































Fig. 12: Chronic viral hepatitis C. Viral antigen (HCV-E2), appearing as positive cytoplasmic granules, is localized in virtually every periportal hepatocyte in this case. (Immunoperoxidase ‘Envision’ technique, using antibody IGH222 – Innogenetics, Ghent, Belgium119)

No accurate noninvasive markers of disease activity and fibrosis Liver biopsy:122,123

o exclude other liver pathologyo establish stage

Autoimmune Hepatitis Several types:

o different patterns of autoantibodies124 May benefit from immunosuppressive therapy

Drug-induced Chronic Hepatitis Always consider when etiology obscure

Cryptogenic Chronic Hepatitis No characteristic features pointing to a particular etiology Disease activity often mild125

Combined PathologyCombined Infection With HBV and HCV

Increases severity of histologic liver lesions126 Triple infection with HBV, HDV, and HCV:

o severe disease in acute superinfection stageo course:

relatively benign slowly progressive usually dominated by HCV127,128

Superinfection Of Chronic Hepatitis B with HDV Usually severe activity with extensive interface hepatitis33,43

HIV Infection Results in reactivation of hepatitis B:

o higher levels of HBV replicationo no increase in necroinflammationo more immunocytochemically demonstrable HBcAg and

HBeAg129 With chronic hepatitis C:

o higher necroinflammatory activityo cirrhosis more frequent130

HGV Virus Infection No apparent effect on chronic hepatitis C131,132

TTV Infection Reported not to affect course of chronic hepatitis B or C and

response to interferon-α therapy133

Multiple Hepatitis Virus Infection Quite common

Cannot be reliably recognized histologically134 Immunocytochemical stains for viral antigens helpful135

Hemochromatosis136 May be foci of hepatocellular hemosiderosis in chronic viral

hepatitis C and B

ClassificationOriginal Classification

Simple classification of chronic hepatitis, based on histology proposed in 1968:137

o immunosuppression was standard treatment reserved for the more ‘active’ forms

o distinguished between: milder form with low level

necroinflammatory activity: chronic persistent hepatitis

(CPH) more severe variants with more severe

necroinflammatory lesions: chronic aggressive or active

hepatitis (CAH)o widely acceptedo used worldwide for nearly 40 yearso emphasized that CPH and CAH were:

variations in degree of disease activity not distinct disease entities

Revised Classification Because more efficient treatment for viral types of chronic

hepatitis32,138–140 In 1994, two proposals:141,142

o restrict term ‘chronic hepatitis’ to original meaning: i.e. clinical and pathologic syndrome:

with several causes characterized by varying degrees

of hepatocellular necrosis and inflammation

still defined (as in 1968) as a continuing disease without improvement for at least 6 months141

o also determine: etiology:

cannot be based on histology alone

consider clinical and serologic data

grade of disease activity stage of disease progression (Table 1)

Table 1. Classification of chronic hepatitis

Diagnosis of chronic hepatitisEtiologyGrade of disease activityStage of disease progression

Differential Diagnosis- Drug Induced Toxic and Liver Injury- Acute Hepatitis

Distinction should be made between: o true ‘lymphocytic piecemeal necrosis’ as in chronic

hepatitiso ‘biliary piecemeal necrosis’ of chronic biliary disease:

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irregular outline of enlarging portal tract due to ductular reaction with associated:

neutrophil infiltration cholate stasis of periportal

hepatocytes143 Wilson's disease:

o may resemble chronic hepatitis clinically and histologically144,145

Alpha-1-antitrypsin deficiency146 Piecemeal necrosis also observed in chronic biliary diseases such

as: o primary biliary cirrhosiso primary sclerosing cholangitis

Without Interface Hepatitis Resolving acute hepatitis Nonspecific inflammation Primary biliary cirrhosis Lymphoma

With Lobular Lesions Distinguish from acute hepatitis Orcein staining helps identify older collapse Ground glass hepatocytes testify to chronicity in hepatitis B Bilirubin stasis much more frequent in acute hepatitis

With Interface Hepatitis Primary biliary cirrhosis Primary sclerosing cholangitis Wilson's disease Alpha-1-antitrypsin deficiency Lymphoma Alertness, special stains, and coordination with clinical

information essential for correct diagnosis

Staging/gradingGrade of Disease Activity

Clinical symptoms Aminotransferase levels Histopathology of liver biopsy:

o main components: portal inflammation interface hepatitis intralobular damage and inflammation confluent necrosis

o several systems: daily practice:

an adequate report consists of accurate estimate of various lesions, described as:

minimal mild moderate severe

for specific purposes, such as comparison of pre- and post-treatment biopsy specimens and for evaluation of therapeutic trials:

semiquantitative scoring systems

Stage Of Disease Progression Evolutionary stage has significant prognostic and therapeutic

implications142 Histologic evaluation based on:

o extent of fibrosiso development of cirrhosis

Connective tissue stains are essential for staging Can be expressed in classical descriptions:

o appropriate method for daily reporting of biopsies For specific purposes, semiquantitative scoring systems

Semiquantitative Scoring Several systems proposed as applied in other areas of diagnostic

histopathology147–162 Histological Activity Index (HAI or Knodell index)

o published 1981158o most widely used

Simple scoring system proposed by Scheuer:162o easily applicable and reproducible154

Modified HAI: o extension of Knodell system, with modifications156o validated for intra- and interobserver variability163

Chronic hepatitis C system proposed by French METAVIR Cooperative Study Group:150,151

o widely applied, especially for staging164,165 Different scoring systems have different strengths and

weaknesses150,166–172 Histologic scoring:

o reserve for special purposes: comparing pre- and post-treatment biopsies

of a single patient as a research method for studying course of

disease as a tool in clinical therapeutic trials153

Choose most suitable system for: o grading173o staging174o use:

clinical practice investigative work166

Define criteria for each score as strictly as possible156,172 Scoring carried out by at least two observers152 Control intra- and interobserver variation:167

o accurate meta-analysis not possible172

Other systems A mathematical scoring system:

o based on fractal geometry for quantifying irregular pattern of liver fibrosis175

Morphometry173 and image-analysis quantification:177–179o appear more sensitive than semiquantitative scoring in

detecting smaller changes in degree of fibrosis Restricted to specialized centers Best used in combination with semiquantitative histologic

evaluation systems178

ManagementAutoimmune Hepatitis

Immunosuppressive treatment reduces severity of necroinflammation and fibrosis180

CIRRHOSISDefinitionDiffuse hepatic fibrosis and replacement of normal hepatic architecture by parenchymal nodules separated by fibrous tissue. The end stage of a variety of chronic liver disorders.

Clinical Features End stage of many chronic liver diseases

Histopathology Diffuse hepatic fibrosis:




























o replacement of normal lobular architecture by parenchymal nodules separated by fibrous tissue1

Portal–central septa linking portal tracts and central veins: o important component

Histologically best appreciated on reticulin stain2 Variable hepatocellular features of individual nodules such as:

o steatosiso siderosiso ground glass hepatocytes

Morphologic Classification Based on size of nodules1

o micronodular: nearly all nodules <3mm diameter (Fig. 1)

Fig. 1: Detail from micronodular cirrhosis. (Reticulin silver impregnation)

o macronodular: nearly all nodules >3mm diameter (Fig. 2)

Fig. 2: Detail from macronodular cirrhosis. Note larger nodules, thin, fibrous septa, and irregular orientation of liver cell plates. (Reticulin silver impregnation)

o mixed micro-macronodular:o ≈ equal numbers of nodules > and <3mm diameter

Needle Biopsy SpecimensMicronodular and Macronodular Cirrhosis

Nodular size determines ease with which diagnosis can be made Nodularity and septa may be readily evident in micronodular

cirrhosis More subtle criteria for macronodular cirrhosis including:

o fragmentation of biopsy specimen: especially with slender tissue cylinders

provided by thin aspiration type needleso thin layers of connective tissue adhering to rounded

edges of nodular biopsy fragmentso abnormal orientation of reticulin fibers due to different

rates of parenchymal growth in different areaso portal tracts and central veins:

abnormal spacing excess numbers of draining veins in relation

to number of portal tractso presence of minute and poorly formed portal tracts

(‘mini-portal tracts’)o hepatocellular features of regeneration:

double-cell plates over widespread areas different appearance of hepatocytes in

adjacent areas liver cell dysplasia:

large cell small cell

Incomplete Septal Cirrhosis Most difficult type to recognize (Fig. 3)

Fig. 3: Detail from ‘incomplete septal type’ cirrhosis. Can be considered a macronodular variety of cirrhosis with large multilobular nodules, thin, incomplete septa, and little inflammatory activity. (Sirius red stain)

Characterized by: o vague nodularityo slender septa:

some end blindlyo mini-portal tractso excess efferent veinso sinusoidal dilatation

Parenchymal hyperplasia with compression of reticulin fibers in adjacent areas

Absent or minimal: o inflammationo necrosis3

Histologic Activity Should be noted May reflect ongoing disease even in cirrhotic stage Activity consists of:

o various forms of liver cell damage and inflammation seen in precirrhotic stage e.g.:

interface hepatitis in posthepatitic cirrhosis steatohepatitis in cirrhotic alcoholics and

NASH












Inactive cirrhosis characterized by; o (near) absence of necroinflammatory lesionso sharp delineation between paucicellular septa and

nodules

Complications In hypoperfusion:

o nodular infarction: i.e. coagulation necrosis of entire nodules

or their centers4 In nonbiliary cirrhosis:

o severe bilirubin stasis: often seen in decompensation phase2

Hepatocellular carcinoma: o common in cirrhotic livero putative precancerous markers and stages:

macroregenerative nodules dysplastic foci and nodules large cell and small cell liver cell dysplasia5

DiagnosisIncomplete Septal Cirrhosis

Diagnosis easier in surgical than needle specimens Borderline between cirrhosis and various forms of noncirrhotic

portal hypertension6,7

Ease With Which Cirrhosis Is Diagnosed Depends on:

o type of specimen: surgical needle

o type of needle used: aspiration type Tru-cut Transjugular

o quality of applied reticulin stains Sometimes histopathologist can only hint at possibility of cirrhosis Complicating factors are:

o dynamic nature of processo may take months or years to develop:

cirrhosis may be: developing incipient fully developed advanced

Etiologic Diagnosis Size of nodules has some use in defining etiology:

o but micronodular cirrhosis may convert into macronodular type8

Pattern of Nodules And Fibrosis Biliary cirrhosis:

o garland-shaped noduleso progressive nature reflected in a clear halo in nodular

periphery due to: edema cholate stasis ductular reaction

Cardiac-type cirrhosis or cardiac sclerosis: o nodules centered by normal-looking portal tractso due to chronic venous outflow obstruction leading to

central–central fibrous septa9 Ductopenia:

o indicates vanishing bile duct disease:

most frequently: in adults:

primary biliary cirrhosis

primary sclerosing cholangitis

in children and young adults: other ductopenia

syndromeso ductular reaction (cholangiolitis) reflects active,

ongoing biliary disease Hepatic venous lesions such as occlusion, narrowing, or

recanalization: o may suggest venous outflow block as causeo also occur in other types of cirrhosis10

May be steatohepatitis in: o cirrhotic alcohol abusers (ASH)o teetotal patients (NASH):

may be no etiologic markers (cryptogenic cirrhosis) in NASH11

Features of activity (necroinflammation) as in precirrhotic chronic hepatitis:

o indicate posthepatitic cirrhosis Ground glass hepatocytes and demonstration of HBsAg, HBcAg,

HBeAg or HbxAg: o help in recognizing HBV infection

Lymphoid aggregates and lymph follicles: o suggest HCV infection

Numerous plasma cells: o suggest autoimmune hepatitis

Etiologies Identified On Finding Intracellular Deposits Severe parenchymal siderosis:

o in genetic hemochromatosis12 Deposits of copper (rhodanine stain) and metallothionein (orcein

stain): o in cirrhosis of different etiologies:

perinodular copper suggests biliary disease positive staining of entire nodules in

Wilson's disease, though other nodules may be negative

abundant copper deposition in Indian childhood cirrhosis13

copper and copper-binding protein sometimes detected in cirrhosis of any etiology14

Eosinophilic, PAS positive, and diastase resistant hepatocellular inclusions:

o alpha-1-antitrypsin deficiencyo best recognized by specific immunostaining15

Differential Diagnosis- Focal Nodular Hyperplasia- Nodular Transformation- Liver Cell Carcinoma

Other nodular and fibrotic conditions of liver: nodular regenerative hyperplasia congenital hepatic fibrosis focal nodular hyperplasia (Table 1):

Table 1. Differential diagnosis of cirrhosis

Disease Diffuse involvement of the liver

Septa

Nodules

http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70827-0#tbl1














Cirrhosis + + +Nodular regenerative hyperplasia

+ – +

Focal nodular hyperplasia

– + +

o may resemble ductopenic biliary cirrhosis

DRUG INDUCED AND TOXIC LIVER INJURY

DefinitionLiver injury due to medications or other toxic agents. Can resemble any liver process; clinical correlation essential in diagnosis.

Clinical Features >600 potentially hepatotoxic drugs identified1

Predictable Reactions Dose dependent All exposed individuals Latent period:

o relatively shorto variable

Reproducible in experimental animals Examples:

o acetaminophen (paracetamol) overdose Not main problem in therapeutic practice

Unpredictable Reactions Compared with predictable reactions:

o of more concern2o more frequent

Only small fraction of population exposed No clear dose relationship Latent period:

o may be quite long: weeks/months

Not reproducible in experimental animals Conclusive proof of responsibility of particular drug or

combination of drugs often impossible to obtain Inadvertent re-challenge may provide strong circumstantial

evidence, even years after first episode3

Bile Duct Damage And Ductopenia Cholestasis usually prolonged:

o may be months–years4

Pathogenesis Liver is main site of biotransformation of endo- and xenobiotics

Predictable Reactions Due to intrinsic hepatotoxicity of molecule

Unpredictable Reactions May be based on:

o genetically determined differences in drug metabolism: i.e. metabolic idiosyncrasy

o immunological reactions to neoantigens formed by interaction between drug metabolite and tissue or cell membrane component:

i.e. immuno-allergic idiosyncrasy2,5

Elementary LesionsZonal Distributions

Due to predominance of microsomal biotransformation enzymes in centrilobular zone

Hepatocytes in Centrilobular Area Ground glass appearance:

o due to hypertrophy of smooth endoplasmic reticulum with associated enzyme induction

o causes include: phenobarbital rifampin (rifampicin) dioxin6

o reflects adaptation rather than injury Increased accumulation of lipofuscin:

o induced by prolonged intake of drugs such as: phenacetin aminopyrine (aminophenazone) chlorpromazine Cascara Sagrada7 anticonvulsant therapy8

Periportal Hepatocytes Ground glass inclusions:

o induced by alcohol aversion drugs (cyanamide)9

Steatosis Frequently occurring effect of xenobiotics Macrovesicular steatosis:

o causes: carbon tetrachloride methotrexate ethanol10

Microvesicular steatosis: o apparently due to inhibition of mitochondrial fatty acid

β-oxidation and mitochondrial dysfunction11o causes:

alcohol intravenous tetracycline amiodarone valproate acetyl salicylate in children (Reye's

syndrome)12,13 several antiviral nucleoside analogs (e.g.

fialuridine)14

Phospholipidosis Causes:

o Coralgil (4,4-diethylamino-ethoxy-hexestrol)o perhexiline maleateo amiodarone15

Cholestasis Simple drug-induced cholestasis:

o causes include: anabolic and contraceptive steroids:

o mechanisms:
















multiple and complex16 Most drugs causing cholestasis or cholestatic hepatitis are

substrates for transporting polypeptides on canalicular membrane17

Hepatocellular Death Caused by cytokines and their cognate receptors18 Induced by:

o toxic drug metaboliteso immunoallergic hypersensitivity reactions

Hepatocellular NecrosisCentrilobular Necrosis

Produced by larger doses of: o most hepatotoxic drugs e.g.:

chloroformo acetaminophen

hepatic poisons e.g.: the mushroom Amanita

phalloides carbon tetrachloride

Periportal Necrosis Produced by other chemicals e.g.:

o ferrous sulfateo yellow form of inorganic phosphorus

Hepatocellular Tumors Best known causative agents:

o oral contraceptives: may be responsible for development of

benign liver cell adenoma debated whether induce hepatocellular

carcinoma –risk lowo anabolic–androgenic steroids:

may induce: adenomas peliosis

o thorium dioxide:19 Thorotrast – used as a radiologic contrast

medium between 1920s and mid 1950s has caused:

hepatocellular carcinoma angiosarcoma cholangiocarcinoma19

Bi- And Multinucleated Hepatocytes Increased number of binucleated hepatocytes:

o cause: sulindac

Multinucleated hepatocytes: o cause:

some instances of acute and chronic drug-induced hepatitis (e.g. clometacin)20

Hepatic Granulomas ≈60 drugs incriminated including:21

o sulfonamideso methyldopao phenylbutazone

Fibrin ring granuloma: o hypersensitivity to allopurinol22,23

Mineral oil granulomas: o may be related to:

absorption and deposition of mineral oil: taken as laxative

ingested as food additive or food contaminant from food packaging24,25

liver steatosis26

Periportal Sinusoidal Dilatation Related to oral contraceptive use May be associated with inflammatory disease27

Peliosis Hepatis Has been associated with:

o anabolic– androgenic steroidso contraceptive steroidso azathioprine28

Angiosarcoma Has been ascribed to:

o inorganic arsenicalso Thorotrasto anabolic–androgenic steroidso oral contraceptiveso vinyl chlorideo radium therapy27

Hepatic Stellate Cell Hyperplasia Observed in:

o hypervitaminosis A29o methotrexate therapy30

Bile Duct Damage And Ductopenia Causes:

o chlorpromazineo haloperidolo ajmalineo glycyrrhizino amoxicillino floxacillin (flucloxacillin)31

Vascular Lesions Thrombosis of hepatic veins and portal vein branches:

o rare complication of contraceptive steroids Veno-occlusive disease or nonthrombotic narrowing of central

vein lumina by loose connective tissue: o causes:

pyrrolizidine alkaloids radiation antineoplastic agents conditioning for bone marrow

transplantation27 Phlebosclerosis of portal vein branches:

o causes: long-term use of inorganic arsenicals

(Fowler's solution) Thorotrast vinyl chloride vitamin A azathioprine methotrexate27

Composite PatternsDrug-induced Acute Hepatitis

An immuno-allergic idiosyncratic type reaction Numerous drug causes including:

o isoniazido halothane




















o indomethacin

Drug-induced Chronic Hepatitis In a small number of patients after prolonged or repeated

exposure to some drugs Incriminated drugs include:

o nitrofurantoin32 phenytoin33

Drug-induced Steatohepatitis Causes:

o amiodarone34o parenteral nutrition35

Histopathology Variety of:

o structural and functional changes in all cellular components

o composite patterns

Elementary LesionsZonal Distributions

Hepatocytes in centrilobular area: o ground glass appearanceo increased accumulation of lipofuscin:

differentiate from pigment accumulation in Dubin–Johnson syndrome

Periportal hepatocytes: o ground glass inclusions:

resemble those in viral hepatitis B, Lafora's disease and glycogenosis type IV

o can be immunostained using a monoclonal antibody against Lafora bodies (KM279) with specificity for polyglucosan36

Steatosis Hepatocellular fat accumulation Macrovesicular steatosis Microvesicular steatosis:

o fine-droplet fatty changeo may be associated clinical manifestations of severe

liver injury in absence of overt hepatocellular necrosis

Phospholipidosis Phospholipid accumulation resulting in:

o foamy cytoplasmic vacuoleso enlargement of hepatocytes and Kupffer cells

Electron microscopy: o lamellated myeloid bodies (fingerprints) in enlarged

lysosomes

Cholestasis Simple drug-induced cholestasis:

o bland bilirubin stasis

Hepatocellular Death If dose of drug or poison:

o sufficient: necrosis usually fatal and massive

o smaller: apoptosis of liver cells with time, may result in fibrosis and

cirrhosis37

Hepatocellular Necrosis

May be: o variable appearance:

coagulative or lytico variable topography:

centrilobular periportal

o variable extent: focal zonal bridging lobular multilobular

Centrilobular Necrosis Associated:

o ballooning and steatosis in adjacent non-necrotic parenchymal cells

o no or little inflammatory infiltration38

Kupffer Cells Involved in:

o storage of foreign materialso granuloma development

Materials Stored In Kupffer Cells Include:

o talc and cellulose: in drug addicts

o silica and anthracotic pigment: in coal miners,

o polyvinyl pyrrolidone and hydroxyethyl starch:39 from infusion of plasma expanders

o silicone: from prosthetic heart valve devices

o Thorotrast40

Hepatic Granulomas Variants include:

o fibrin ring granuloma22,23o mineral oil granuloma:

composed of lipophages in portal tracts and near central veins

Gold identified in lipophages and granulomas when gold therapy used for rheumatoid arthritis41

Hepatic Stellate Cell (Ito Cell) Hyperplasia Increased number of hepatic stellate cells with prominent lipid

vacuoles per unit volume of liver tissue May be associated pericellular and septal fibrosis

Vascular Lesions May affect all intrahepatic blood vessels Phlebosclerosis of portal vein branches:

o if thrombosis, may lead to nodular regenerative hyperplasia25

Arteritis: o may affect intrahepatic branches of hepatic artery,

resulting in: multifocal hemorrhagic necrosis exceptionally rupture of liver27

Composite Patterns Histopathology combines several elementary lesions in varying

proportions

Drug-induced Acute Hepatitis















Histopathology virtually indistinguishable from acute viral hepatitis

Combines: o hepatocellular damage and death:

variable degreeo portal and parenchymal inflammation:

variable extent

Drug-induced Chronic Hepatitis Elementary lesions of chronic hepatitis in various stages, including

cirrhosis No specific histologic lesions

Drug-induced Steatohepatitis Resembles acute hepatitis of alcoholic type

Drug-induced Cholestatic Hepatitis Lesions of acute hepatitis with moderate or marked bilirubin

stasis May be prominent eosinophils in inflammatory infiltrate

Drug-induced Granulomatous Hepatitis Combines features of:

o usually mild hepatitiso noncaseating granulomas

If bilirubin stasis and infiltration of eosinophils, virtually diagnostic for drug-induced liver disease42

Special Stains and ImmunohistochemistryDrug-induced Chronic Hepatitis

Autoantibodies may cause confusion with autoimmune hepatitis43

Diagnosis Recognition difficult because:44

o may mimic any naturally occurring liver diseaseo occurs with compounds from all classes of

drugs2,45,46o may not be clinical signs of a hypersensitivity reactiono drug histories often not reliableo often impossible to pinpoint causative agent if on

multiple drug therapyo same drug may cause different patterns of liver

damage in different patients47o hepatotoxicity may not yet have been reported for a

particular drug, even after a long time on the marketo liver damaging effect may be accentuated by

concomitant administration of other pharmacologic agents

Specific sources of information include: o Books1,48o Reviews49–53

Always maintain high degree of suspicion:54o especially:

in elderly if on histopathology:

resembles viral hepatitis: with

disproportionately severe parenchymal necrosis in relation to clinical condition

associated: steatosis granuloma

s

infiltration by eosinophils

bile duct damage55

centrilobular necrosis sharply delineated from non-necrotic parenchyma, especially if:

associated steatosis only mild or minimal

inflammation numerous ceroid

macrophages55 parenchymal giant cell hepatitis

in adult hepatocyte necrosis with veno-

occlusive disease56

Drug-induced Chronic Hepatitis Diagnosis:

o important: may be cured by withdrawal of drug

o relies on: high degree of suspicion in absence of viral

markers close cooperation from clinician and patient

Drug-induced Granulomatous Hepatitis Virtually diagnostic for drug-induced liver disease if:

o bilirubin stasiso infiltration of eosinophils

Differential Diagnosis- Chronic Hepatitis- Acute Hepatitis- Cholestasis- Steatohepatitis- Granuloma

Bile Duct Damage And Ductopenia Differential diagnosis includes most vanishing bile duct diseases

Drug-induced Cholestatic Hepatitis Differentiation from bile duct obstruction relies on absence or low

expression of typical obstructive features such as: o portal edemao neutrophil-associated ductular proliferation

Severe liver cell damage and marked inflammation are more suggestive of:

o viral hepatitiso viral-like drug-induced acute hepatitis

STEATOSIS AND STEATOHEPATITISSTEATOSISDefinitionAccumulation of triglycerides in the hepatocytic cytoplasm, usually indicating reversible liver damage. Divided into macrosteatosis and microsteatosis, the latter being seen in life-threatening conditions such as Reye's syndrome.

Clinical Features Common Hepatomegaly May be elevated serum:

o aminotransferaseso alkaline phosphataseo γ-glutamyl transpeptidase













Microvesicular Steatosis Potentially life threatening Frequently disturbed liver function and coma1 Effects on other tissues If survival, no long-term effects on liver

Reye's Syndrome Mainly young children Presentation:

o acute mild viral illness followed by: vomiting lethargy coma

o fatal in about one-third of patients

Pathogenesis Complex:

o alterations at many points in lipid metabolismo lead to accumulation of neutral fat within

hepatocytes2,3 Manifestation of reversible cell injury4 Nonspecific Variety of causes:

o minor amount: uncertain significance more frequent in elderly5

o more extensive: variety of primary hepatic diseases several systemic conditions

Microvesicular Steatosis Impaired of β-oxidation of lipids Multiple causes include:

o acute fatty liver of pregnancyo Reye's syndrome:

may be: attributable to salicylate use6 sometimes related to inherited

metabolic disorder of mitochondrial β-oxidation:7

many patients have defects in fatty acid oxidation

form of primary mitochondrial hepatopathy8,9

Causes Therapeutic drugs including:

o salicylates: Reye's syndrome

o sodium valproateo intravenous high dose tetracycline10

Ethanol: o small proportion of patients:

alcoholic foamy degeneration Fulminant hepatitis D:

o in Amazon basin11 Multiple hornet stings12 Inborn errors of mitochondrial fatty acid β-oxidation Inherited urea cycle disorders13

Histopathology Accumulation of triglycerides in cytoplasm of hepatocytes:

o variable degree: may be:

occasional fat droplets

diffuse deposition involving most parenchymal cells

Patterns and Distribution Two patterns:

o macrovesicular steatosis: most common

o microvesicular steatosis Both patterns may be in same biopsy specimen:

o suggests that large droplets form through coalescence of small lipid vacuoles

Macrovesicular Steatosis Large droplet fatty change (Fig. 1)

Fig. 1: Hepatic steatosis in patient with alcohol abuse. The picture shows a mixture of macrovesicular and microvesicular steatosis and a lipogranuloma (upper right corner). (H&E)

Single large vacuole: o distends hepatocyteo displaces nucleus to one side

If uncomplicated used to be regarded as benign and potentially fully reversible:

o this notion has been challenged14,15 Variable zonal distribution and although exceptions:

o most often centrilobular, e.g. in: alcoholic liver disease obesity diabetes

o may become panlobular when more severeo when in periportal zones more common in:

cachexia and protein–energy malnutrition (kwashiorkor)

AIDS after total parenteral nutrition phosphorus poisoning steroid therapy

Severity Mild:

o less than one-third parenchyma involved Moderate:

o one-third to two-thirds parenchyma involved Severe:

o more than two-thirds parenchyma involved

Microvesicular Steatosis Small droplet fatty change (see Figs 1 and 2)

















Fig. 2: Acute fatty liver of pregnancy. Detail of lobular parenchyma characterized by microvesicular steatosis and a small number of lymphocytes. (H&E)

Often more difficult to recognize than macrovesicular steatosis Demonstration may require histochemistry

Reye's Syndrome Panlobular steatosis:

o smaller droplets in centrilobular areaso somewhat larger fat vacuoles in periportal regions

May be necrosis of periportal hepatocytes

Lipogranuloma Focal response to rupture of lipid-laden hepatocytes Contains:

o macrophageso occasional lymphocyteso eosinophilso sometimes giant cells (see Fig. 1)

May be: o abundant:

especially in alcohol-induced steatosiso confluento fat-laden macrophages within portal tracts16

Lead to focal fibrosis without great clinical significance

Focal Steatosis Sometimes an isolated finding Usually under liver capsule

Special Stains and Immunohistochemistry In routinely fixed tissue:

o cytoplasmic vacuoles because lipid dissolved during processing

Very small droplet steatosis may be difficult to recognize Histochemical staining helpful:

o lipid demonstrated in: frozen sections using:

oil red O Sudan black

o tissue postfixed in osmium tetroxide17

Diagnosis Not possible to define etiology on pattern of lipid distribution in

individual case: o identification of cause requires close clinicopathologic

correlation Important information in report:

o severityo a mixed pattern of macro- and microvesicular

steatosis: may be of prognostic importance in

alcoholic liver disease18

Other investigationsFocal Steatosis

Identified by modern imaging techniques May be other coincident liver pathology Multifocal steatosis resembling metastatic liver disease

radiologically described in AIDS

Differential Diagnosis- Drug Induced Toxic and Liver Injury- Steatohepatitis- Chronic Hepatitis

Lipogranuloma Serial sections may be required to identify central fat globule and

differentiate from other forms of granuloma19 Fat-laden macrophages within portal tracts:

o must be distinguished from mineral oil granulomas in which:

vacuoles are larger and more irregular generally more fibrosis

STEATOHEPATITISDefinitionSteatosis, necroinflammation and fibrosis of liver. Can be alcoholic or non-alcoholic.

Pathogenesis Fatty liver of alcoholic or nonalcoholic etiology:

o can coincide with or lead to: necroinflammation fibrosis1

Steatosis may be a direct cause of more advanced pathology2 Two-hit hypothesis for development:

o first hit: steatosis

o second hit: presence of other factor(s) such as oxidative

stress3 Lipid peroxidation:

o one mechanism linking steatosis to necroinflammation and fibrosis

o causes oxidative stress of the cell interindividual differences in magnitude

explain individual susceptibility i.e.:3,4 in chronic alcoholics:

alcoholic steatohepatitis (ASH)

people who do not consume alcohol:

nonalcoholic steatohepatitis (NASH)

Oxidizable fat within liver is enough to trigger lipid peroxidation5

NASH Causes include:

o jejunoileal bypass surgeryo gastroplastyo other causes of rapid profound weight loss in obese

subjectso total parenteral nutritiono drugs:

amiodarone perhexiline maleate estrogens and estrogen receptor ligands methotrexate

o occupational hepatotoxicity:













as at a petrochemical plant in Brazil6o copper toxicityo disorders with extreme insulin resistance

Usually: o etiopathogenesis appears multifactorial:

i.e. obesity, type 2 diabetes, and hypertriglyceridemia7

o can be regarded as hepatic consequence of: metabolic syndrome cardiovascular dysmetabolic syndrome syndrome X8

May be relationship with cryptogenic cirrhosis through shared risk factors of obesity and diabetes9

HistopathologyASHEarly Stages

Predominantly centrilobular zones Usually all lobules Constellation of changes:

o not all present in individual caseo variation without correlation with clinical and

biochemical data in: severity extent of lobular involvement

Steatosis: o commono usually macrovesicular:

worse prognosis if mixed macro- and microvesicular pattern15

even worse prognosis if almost panlobular, predominantly microvesicular steatosis with canalicular bilirubin stasis:

i.e. alcoholic foamy degeneration16

o strong correlation between degree (without steatohepatitis) and number of activated hepatic stellate cells17 stimulated by ethanol metabolites in absence of necroinflammation18

Fibrosis: o constant feature:o different patternso identification requires collagen stains

Most Essential FeaturesLiver Cell Injury

Ballooned hepatocytes: o may contain Mallory bodies:19–22

i.e. perinuclear inclusions (Fig. 1) that are:

Fig. 1: Acute alcoholic hepatitis (ASH). Detail of centrilobular parenchyma, characterized by pericellular fibrosis, steatosis, hydropic swelling of several hepatocytes containing Mallory bodies, and neutrophils swarming around hydropic parenchymal cells (satellitosis). (H&E)

homogeneous eosinophilic variable size and shape complex structures composed

of: aggregated

hyperphosphorylated cytokeratin polypeptides:

including cytokeratins 7, 18, and 19

ubiquitin heat shock proteins tan proteins

easily discernible in routinely stained sections in florid cases

may be small and difficult to identify in mild disease:

immunostaining of cytokeratins or ubiquitin helpful

Liver cell death by: o necrosiso apoptosis23

Inflammatory Infiltrates Predominantly neutrophil polymorphs:

o often surround and even invade hepatocytes containing Mallory bodies:

i.e. satellitosis

Pericellular (or Perisinusoidal) Fibrosis24 So-called ‘chicken-wire fibrosis’ (Fig. 2)

Fig. 2: Acute alcoholic hepatitis (ASH). Detail of centrilobular zone, showing fibrous obliteration of the centrolobular vein (veno-occlusive lesions; center) and marked pericellular (‘chicken-wire’) fibrosis. (Sirius red stain)

Ensheathes pillars of hepatocytes25 Possibly:

o perivenular fibrosis:

















lumen of central veins may be narrowed or occluded by subendothelial fibrosis14

o phlebosclerosis In a minority:

o centrilobular confluent areas with parenchyma replaced by:

fibrosis central–central bridging fibrosis:

originally described as sclerosing hyaline necrosis26

May be: o macrophageso lymphocyteso apoptotic bodies from dying hepatocyteso some bilirubin stasis

Less Essential Features Giant mitochondria:

o round, oval, or cigar-shaped inclusions: variable size eosinophilic PAS–diastase negative

o better visualized with: chromotrope–aniline blue (CAB) stain immunohistochemistry27

o not specific for alcohol-induced liver disease28 Veno-occlusive lesions: Ductular metaplasia29

Later Stages Fibrosis extends to lobular periphery Necrotic bridges and fibrous septa link central veins with portal

tracts: o obscure lobular topographyo together with parenchymal regeneration, lead to

cirrhosis30 A semiquantitative scoring system suitable for alcoholic fibrosis

published31 Cirrhosis of alcoholic origin:

o micronodularo ongoing superimposed steatohepatitis:

worsens prognosis32 suggests etiology

ASH vs NASH No qualitative histologic differences33–35 When large groups of patients compared:

o alcoholics tend to develop more severe diseaseo NASH usually associated with:

more: fat nuclear glycogen

less: hepatocellular damage inflammation fibrosis Mallory bodies

DiagnosisASH

Alcoholic etiology suspected (but not proved) by: o micronodular patterno dense fibrosis blurring nodular edgeso steatosiso central vein occlusions

Liver biopsy quite useful for diagnosis36

NASH Need for consensus to establish diagnosis regarding:

o minimal histologic criteria: histologic criteria proposed37 include

patterns of injury similar to features of alcoholic injury

not agreed upon by all investigators38–42o maximum amount of alcohol intake43

Subclassification proposed to include etiopathogenesis: o primary NASH:

related to obesity and insulin resistanceo secondary NASH:

post bypass surgery drugs toxins37

Term nonalcoholic fatty liver disease (NAFLD) proposed to incorporate spectrum of steatotic syndromes not induced by alcohol41

Not all lesions of alcoholic liver disease in NASH Not all lesions of NASH in alcoholic liver disease33 A system for grading and staging histologic lesions in NASH

published

Differential Diagnosis- Drug Induced Toxic and Liver Injury- Chronic Hepatitis- Steatosis

ASHViral Hepatitis

May be suspected clinically, but liver histopathology different

Chronic Venous Congestion May be confusion if incomplete picture of ASH, with only

perivenular and pericellular centrilobular fibrosis

Diseases Unrelated To Alcohol Mallory bodies, neutrophils, and fibrosis are part of

histopathology of diseases unrelated to alcohol such as: o chronic cholestasis:

easy to differentiate due to periportal predominance of changes

o Wilson's disease: always consider, especially in younger

patients

Hypervitaminosis A May cause pericellular fibrosis progressing to cirrhosis45

Hepatocellular Siderosis In some alcoholics May be confused with genetic hemochromatosis:

o may be solved by: quantitative tissue iron determination calculation of hepatic iron index46

NASH Identical histopathology

ManagementASH

On stopping alcohol: o parenchymal regeneration improveso nodules increase in sizeo all features of alcoholic etiology disappear




















CHOLESTASIS AND BILIARY DISEASESCHOLESTASISDefinitionBile accumulation in the liver. Could be mechanical or functional.

Clinical Features May be acute or chronic Acute:

o usually: complete due to either:

total functional exocrine secretory failure of hepatocytes e.g.:

drug-induced cholestasis

complete obstruction of extrahepatic bile ducts e.g.:

impacted gallstone Chronic:

o indicates longer duration cholestatic condition (weeks, months, years)

o may be: complete e.g.:

chronic total extrahepatic bile duct obstruction by carcinoma of pancreas or

variably incomplete e.g.: primary biliary cirrhosis primary sclerosing cholangitis).

o if incomplete may remain anicteric for long periods

Pathogenesis Arrest or marked reduction in bile secretion and bile flow due to:

o functional secretory disturbances of hepatic parenchymal cells1

o obstruction at any level in excretory pathways of bile, from canaliculi to papilla of Vater2

Intrahepatic Cholestasis Cause:

o primary focus inside liver: diseases of:

parenchymal cells intrahepatic bile ducts sometimes both parenchymal

cells and intrahepatic bile ducts1

Extrahepatic Cholestasis Cause:

o bile excretory block in larger ducts: outside liver along extrahepatic bile ducts

e.g.: gallstones bile duct tumors bile duct strictures

in larger hilar intrahepatic ducts

Combined Intra- And Extrahepatic Cholestasis Involves both:

o intrahepatic segments of biliary treeo extrahepatic segments of biliary tree

Examples: o extrahepatic bile duct atresia in neonateso primary sclerosing cholangitis in adults and children

Block in bile secretion: o may be:

complete: total arrest of bile secretion retention of:

bile salts bilirubin

functional or obstructive incomplete

usually incomplete or partial obstruction of: intrahepatic bile ducts:

mostly due to destructive diseases of intrahepatic bile ducts (vanishing bile duct diseases) such as:

primary biliary cirrhosis primary sclerosing cholangitis

extrahepatic bile ducts: incomplete obstruction (narrowing or

strictures) of segments of larger bile ducts

retention of: bile salts (but not bilirubin)

HistopathologyAcute Complete Cholestasis

Changes in: o lobular parenchymao portal tracts

Bilirubin accumulation in liver lobule (Fig. 1):

Fig. 1: Marked bilirubin stasis in hepatocytes, canaliculi, and Kupffer cells in neonate with extrahepatic bile duct atresia. (H&E)

o starts in centrilobular zoneo pigment granules in parenchymal cells:

hepatocellular bilirubin stasiso inspissated bilirubin-stained bile plugs in dilated

intercellular canaliculi: canalicular bilirubin stasis

Hypertrophic Kupffer cells: o phagocytose debris resulting from hepatocellular

damage and death due to retention of detergent bile acids, i.e.:

dying parenchymal cells liberated canalicular bile plugs

o Kupffer cell bilirubin stasis indicates at least several days' duration3

Edema of portal tract connective tissue: o especially if extrahepatic obstructive origino results in:

some rounding of portal contours incipient ‘ductular reaction’

Chronic Complete Cholestasis








Parenchymal changes appear with time superimposed on early bilirubin stasis

Bilirubin stasis: o gradually extends toward periportal parenchyma

Lymphocytic inflammatory infiltrate: o restricted to area with bilirubin stasiso mildo in most forms lasting for weekso apparently secondary to cholestatic changes

Chronic Incomplete Cholestasis Bilirubin stasis not a feature:

o except if: terminal decompensating phase superimposed pathologic changes:

e.g. drug-induced liver damage

Histopathologic Diagnosis of Chronic Cholestasis Applies to both complete and incomplete chronic cholestasis Parenchymal, portal, and periportal alterations as outlined below

Parenchymal Changes Include:

o cholate stasiso cholestatic liver cell rosetteso feathery degenerationo xanthomatous cellso bile infarcts

Cholate Stasis Periportal hepatocyte lesion:

o thought to be due to membrane-damaging effect of retained bile acids4

Hepatocytes: o swollen (Fig. 2)

Fig. 2: Cholate stasis in periphery of parenchymal nodule in cirrhotic liver of patient with end stage primary sclerosing cholangitis. The hepatocytes near the fibrous septum (lower part) show hydropic swelling, clumping of the cytoplasm, and Mallory bodies. (H&E)

o paleo coarsely granular:

contain granules of lysosomal copper, complexed with copper-binding protein (metallothionein):

stainable with: rhodanine (copper)

(Fig. 3)

Fig. 3: Cholate stasis in periphery of cirrhotic nodule in patient with stage 4 primary biliary cirrhosis. Lysosomal copper–metallothionein complexes appear as red-stained granules in the copper-specific rhodanine stain.

orcein (metallothionein) (Fig. 4

Fig. 4: Cholate stasis in periportal parenchyma in patient with primary sclerosing cholangitis. The picture shows orcein-positive granules in periportal hepatocytes, representing lysosomal localization of copper binding protein (metallothionein). (Orcein stain)

)o with time:

contain Mallory bodieso very late stages:

may be bilirubin inclusions

Cholestatic Liver Cell Rosettes Useful diagnostic feature5 Tubular rearrangement of liver cell plates that are normally one

cell thick Glandular or tubular structures:










o lined by four or more hepatocytes: may show feathery degeneration

o central lumen: may:

vary greatly in diameter (Fig. 5)

Fig. 5: Cholestatic liver cell rosettes. Liver biopsy of patient with primary sclerosing cholangitis. The involved hepatocytes appear in tubular arrangement. (H&E)

appear empty be filled with eosinophilic or

bilirubin-stained material in variable degrees of inspissation

Feathery Degeneration Hydropic swelling of:

o single cellso groups of parenchymal cells

May be some bilirubin impregnation of remaining visible cytoplasm in chronic complete cholestasis

Xanthomatous Cells Feature of longstanding incomplete and complete cholestasis Lipid-laden histiocytes with foamy cytoplasm:

o accumulate in: parenchyma portal tracts

o single or in clusterso represent tissular expression of hyperlipidemia that

accompanies chronic cholestasis

Bile Infarcts So-called Charcot–Gombault infarcts Late parenchymal lesion in severe cholestasis of long duration Mainly in large duct obstruction Lesions consist of necrotic hepatocytes:

o mostly paraportalo possibly bilirubin impregnation of central necrotic areao gradually replaced by organizing mesenchymal tissueo finally result in fibrous scars

Two Further Characteristic Changes In Neonatal Cholestatic Liver Diseases

Parenchymal Multinucleated Giant Cells Due to syncytial fusion of several mononucleated hepatocytes Variable:

o number of nucleio location

Often contain pigment granules corresponding to: o bilirubino lipofuscino hemosiderin

May: o appear necrotico surrounded by neutrophil polymorphs6

Extramedullary Hematopoiesis Foci comprising clusters of:

o erythrocyte precursor cellso myeloid precursor cellso megakaryocytes

Common

Periportal And Architectural Changes Comprise:

o ductular reactiono ductular reabsorptiono periductular fibrosiso biliary fibrosiso final stage of biliary cirrhosis

Ductular Reaction Increased number of ductular profiles in periphery of portal tract:

o gradually extend into periportal parenchyma toward neighboring portal tracts in periphery of liver lobule

o accompanied by: edema neutrophil infiltration (Fig. 6)

Fig. 6: Ductular reaction in chronic cholestasis. Liver biopsy from patient with primary sclerosing cholangitis. The picture shows a mildly inflamed portal tract (upper part) with (at 8 o'clock) a focus of ‘ductular reaction’ composed of bile ductules, edematous stroma, and some neutrophil infiltration. (H&E)

If obstruction of extrahepatic bile ducts: o mainly due to increased bile pressure8,9o involves elongation of pre-existing bile ductules9o has been described as ‘marginal bile duct

proliferation’10 In other cholestatic diseases, not necessarily obstructive:

o proinflammatory cytokines may be predominant triggers11,12

o cholangiocytes lining ductules may show signs of reabsorption:

reflected in vacuolization of cytoplasm accumulation of bilirubin and lipofuscin

Biliary piecemeal necrosis describes:13












o irregular portal–parenchymal interface due to: wedge-shaped periportal extension accompanying inflammation into periportal

parenchyma possibly features of cholate stasis

Periductular Fibrosis Accompanies ductular reaction

Biliary Fibrosis Progressive ductular reaction with periductular fibrosis eventually

results in fibrous linkage of adjacent portal tracts: o i.e. portal–portal septal fibrosiso potentially reversible14 because basic

angioarchitectural pattern of liver preserved15

Biliary Cirrhosis Final stage in disturbance of lobular architecture Characterized – like any cirrhosis – by:

o additional portal–central fibrous septao nodular parenchymal regeneration

Ongoing cholestasis: o characterized by:

persistence of ductular reaction edema periductular inflammation fibrosis

o together with lesions of cholate stasis in nodular periphery creates at low magnification impression of clear halo between cirrhotic nodules and fibrous septa:

indicates actively progressing disease in its cirrhotic stage

Special Stains and ImmunohistochemistryCholate Stasis

Earliest stages: o may be revealed by immunostaining for cytokeratin 7:

reveals a phenotypic switch to a biliary type of intermediate filament cytoskeleton in periportal hepatocytes (Fig. 7)

Fig. 7: Primary biliary cirrhosis. Detail of portal tract and surrounding parenchyma. This cytokeratin 7 immunostain highlights an increase in the number of ductular structures at the portal tract periphery; expression of cytokeratin 7 in periportal hepatocytes (early stage of cholate stasis), and a few scattered, small cytokeratin 7 positive cells at some distance from the portal tract (presumed hepatic progenitor cells). (Immunostain for cytokeratin 7)

With time: o cytokeratin 7 expression extends with decreasing

gradient from limiting plate toward center of the lobule over a distance of several cells16

Cholestatic Liver Cell Rosettes Some or all lining hepatocytes may

o express bile duct-type cytokeratin i.e.: cytokeratin 7 tissue polypeptide antigen (TPA):

indicates partial shift toward bile duct cell phenotype (Fig. 8)

Fig. 8: Cholestatic liver cell rosettes. Immunostaining for cytokeratin 7 reveals cholestatic liver cell rosettes to better advantage. Normal hepatocytes do not express cytokeratin 7, whereas cells in cholestatic rosettes express this intermediate filament to variable extent.

should not be misinterpreted as expression of hepatocellular regeneration

Diagnosis If incomplete and anicteric:

o no microscopically visible accumulation of bilirubin in liver tissue sections

o underscores usefulness of distinguishing between: bilirubin stasis cholate stasis









either separately or in combination may constitute picture of histologic cholestasis19

Basic differences between chronic complete and incomplete cholestasis are:

o absence of bilirubin stasis in incomplete categoryo occasionally more pronounced expression of lesions in

complete variety

Giant Cell Transformation Of Parenchymal Cells Occurs in a variety of conditions Appear to be more specific for age than disease:

o nonspecific reaction of infant's hepatocytes to various types of injury:

o occasionally in adults

Absent Ductular Reaction Chronic states of cholestasis sometimes lack obvious ductular

reaction e.g. may be absent in: o Alagille's syndromeo some cases of:

primary sclerosing cholangitis chronic liver allograft rejection

Differential Diagnosis- Paucity of Interlobular Bile Ducts- Neonatal Giant Cell Hepatitis- Primary Sclerosing Cholangitis- Primary Biliary Cirrhosis- Drug Induced and Toxic Liver Injury

Bilirubin Stasis Dark brown to black deposits (in hepatocytes, canaliculi, Kupffer

cells, and ductules) in erythropoietic protoporphyria: o easily identified by polarized light:

protoporphyrin deposits have a red to yellow birefringence with a Maltese cross configuration in coarser (ductular) deposits (Figs 9 and 10)

Fig. 9: Erythropoietic protoporphyria. Dark brownish-black deposits of protoporphyrin in hepatocytes, canaliculi, Kupffer cells, and ductules. (H&E)

Fig. 10: Erythropoietic protoporphyria. The deposits are birefringent, and show a Maltese cross picture of red birefringence in the larger deposits. (Polarized light)

Extramedullary Hematopoiesis Not a reliable criterion for differentiation between various

cholestatic diseases such as biliary atresia and neonatal hepatitis

Biliary Fibrosis Distinguish from true biliary cirrhosis

Staging/gradingStaging In Chronic Cholestatic Liver Diseases

Based on periportal and architectural changes Stage 1:

o portal Stage 2:

o periportal Stage 3:

o septal Stage 4:

o Cirrhotic

Vanishing Bie Duct DiseasesExtrahepatic Bile Duct AtresiaDefinitionCongenital disorder where there is progressive necroinflammatory destruction of intrahepatic and extrahepatic bile ducts.

Clinical Features May start:

o in uteroo in perinatal period

Pathogenesis Etiology unknown Probably heterogeneous and represents common phenotype of

several underlying disorders1,2

Histopathology Involves both extrahepatic and intrahepatic ducts:

o originally maximal involvement of part or all extrahepatic duct system

Panbiliary Progressive necroinflammatory destruction of bile ducts During first 3–4 weeks:

o mostly nonspecific bilirubin stasiso some parenchymal giant cellso foci of extramedullary hematopoiesis

Gradual development: o portal edemao ductular reaction:







considered most reliable, though not pathognomonic criterion in diagnosing extrahepatic obstruction in liver specimens3

Ductules often contain inspissated bile concrements Later stages:

o periportal fibrosiso finally resulting in secondary biliary cirrhosis

Intrahepatic ducts: o irregularity of lining cholangiocytes, which feature:

vacuolization nuclear pyknosis atrophy infiltration by inflammatory cells (Fig. 1)

Fig. 1: Extrahepatic bile duct atresia (EHBDA). Detail of a portal tract in liver biopsy from neonate with EHBDA, showing mild inflammatory infiltrate, and a bile duct with irregular outline and epithelial damage: vacuolization in some cholangiocytes, apoptosis in others, and some inflammatory cells inside the basement membrane. (H&E)

Thickening of basement membrane Progressive atrophy and disappearance of ducts4 Histopathology of obliterated extrahepatic ducts:

o various stages of: nonspecific inflammation epithelial desquamation and necrosis ulceration fibrosis5,6

Early Severe Variant In >25%7–9 of cases interlobular bile ducts appear in early

embryologic shape: o so-called ‘ductal plate malformation’ (Fig. 2)

Fig. 2: Extrahepatic bile duct atresia (EHBDA), early severe type in stage of advanced fibrosis. The picture shows part of a large, fibrous portal area, with recognizable hepatic artery branches, barely visible or no portal vein branches, and bile duct structures in ductal plate configuration (ductal plate malformation).

The lining cholangiocytes show involutional changes: flattening, shrinkage, and nuclear pyknosis. (H&E)

o suggests antenatal start associated with arrest of remodeling of embryonic ductal plates10

Histology reveals advanced fibrosis, even at 4 weeks of age

Diagnosis Liver biopsy cornerstone in diagnosis

Differential Diagnosis- Drug Induced and Toxic Liver Injury- Neonatal Giant Cell Hepatitis- Inborn Errors of Metabolism

Other causes of obstruction: o mainly choledochal cyst in this neonatal period:o degenerative lesions of intrahepatic ducts

Neonatal giant cell hepatitis: o no or much less ductular reactiono more intralobular than perilobular fibrosis

Chronic liver injury by parenteral nutrition Several inborn errors of metabolism

Management Hepatic portoenterostomy or Kasai operation with resection of

obliterated extrahepatic ducts Correlation between number and size of patent ducts in porta

hepatis at portoenterostomy and success of procedure controversial:11,12

o some assess bile duct luminal size in frozen sections of proximal resection margin during a Kasai procedure

o some consider total diameter of all prehilar structures important, with total diameter >400μm indicating favorable prognosis for adequate bile drainage

Paucity of Interlobular Bile Ducts

DefinitionCongenital disorder where there is destruction and loss of small interlobular bile ducts. Divided into syndromic (Alagille's) and non-syndromic forms associated with alpha-1-antitrypsin deficiency, rubella, Turner's syndrome, trisomy 21 and others.

Clinical Features Subdivided according to associated clinical features into

syndromic and nonsyndromic PILBD Syndromic PILBD:

o Alagille's syndrome or arteriohepatic dysplasiao abnormal facieso vertebral, cardiac, ocular, and renal abnormalities:












according to presence or absence, result in a complete or incomplete syndrome1

o destruction of ducts generally starts after 3 months of age

o early changes do not allow prediction of future development of fibrosis2

Nonsyndromic PILBD: o may be:

isolated hepatic abnormality (idiopathic) one component of more complex systemic

process with or without known cause associated with:

alpha-1-antitrypsin deficiency rubella trisomy 21 Turner's syndrome Byler's disease other conditions

o most frequent diagnosis for conjugated hyperbilirubinemia in first month of life3

o destruction of interlobular ducts starts early (before 3 months) and progression usually faster than in syndromic PILBD2,3

Histopathology Nonspecific, inflammatory destruction of interlobular ducts,

resulting in progressive ductopenia Changes:

o mainly of chronic incomplete cholestasis and neonatal cholestasis

Special Stains and Immunohistochemistry Immunostains for cytokeratin 7 (or 19) or tissue polypeptide

antigen (TPA): o for better visualization of interlobular ducts:4

especially in very young children5

Diagnosis Requires sufficiently large biopsy specimen and quantitative

evaluation of interlobular ducts: o needle biopsy may suffice if contains at least five portal

tracts3o 70–80% of branches of hepatic artery normally

accompanied by duct of approximately similar size near center of portal tract

‘widowed artery’ signals missing duct6 Ratio of number of interlobular ducts to number of portal tracts:

o 0.9–1.8 in normal children and adults7o in PILBD:

originally defined as <0.5 now also defined as a reduced bile duct to

portal tract ratio >0.5: especially when ducts with

degenerative changes8 in premature infants <0.9 may be normal:9

due to incomplete bile duct development at birth

Differential Diagnosis- Extrahepatic Bile Duct Atresia- Drug Inuced Toxic and Liver Injury- Neonatal Giant Cell Hepatitis- Alpha 1 Antitrypsin Deficiency

Primary Biliary CirrhosisDefinition

Autoimmune disorder in middle-age females where there is chronic non-suppurative destruction of bile ducts resulting in cirrhosis. Antimitochondrial antibody to M2 component of pyruvate dehydrogenase is found in 90% of the cases.

Clinical Features Nearly 10× more frequent in females than males Usually insidious onset starting with pruritus

Pathogenesis Considered to be autoimmune:

o often other autoimmune disorderso proof strong, but only indirect and circumstantial1

Gross Pathology Basic lesion:

o chronic, nonsuppurative, destructive cholangitis: possibly ending in cirrhosis2

HistopathologyEarly Stage

Involves ducts 40–80μm diameter: o i.e. segmental and larger interlobular ductso size may be difficult to estimate because some enlarge

apparently through: damage to basement membrane reactive hyperplasia of lining epithelium3

Lesions: o focal in livero segmental within duct system

Affected duct segments: o epithelial swelling or eosinophil condensationo possibly stratificationo infiltration by lymphocytes and plasma cellso damage of basement membrane may lead to rupture

inflammatory cells accumulate beside or around duct (Fig. 1):

Fig. 1: Granulomatous cholangitis in primary biliary cirrhosis (PBC). Detail from a portal tract with dense lymphoplasmacytic infiltrate and lymphoid aggregate (left). The interlobular bile duct (center) shows a focal rupture of its cholangiocytic lining, at the site of an adjacent epithelioid granuloma. (H&E)

mainly lymphocytes: sometimes aggregated in

lymphoid follicle with germinal center

may be: abundant plasma cells quite prominent eosinophils neutrophils single or small clusters of

epithelioid cells:


















sometimes epithelioid granulomas close to or surrounding bile duct

Smaller ducts: o may be surrounded by edema or fibrosis:o presumably result of more distal obstruction

May be parenchymal changes: o lobular infiltration by scattered lymphocyteso nodular regenerative hyperplasia:4

together with narrowing of portal vein branches,5 may explain development of portal hypertension before development of fibrosis and cirrhosis

o lesions of chronic cholestasis absent or minimal

Histologic Progression Most cases within 2 years:

o 20% remain histologically stableo sustained regression in 2%6

Extension beyond limits of portal tract Increasing:

o fibrosiso disturbance of lobular architecture

Appears to be driven by: o periportal and architectural changes of chronic

cholestasiso lymphocytic interface hepatitis (piecemeal

necrosis):7,8intralobular ‘invading’ lymphocytes play role in development of septal fibrosis9 (Fig. 2)

Fig. 2: Primary biliary cirrhosis, stage 3. The picture shows portal–portal septal fibrosis (septal stage 3), portal inflammation with lymphoid aggregate, absence of interlobular bile duct (ductopenia), and cholate stasis in periportal and periseptal parenchyma. (H&E)

may be variable degree of intralobular necroinflammation10

May be liver cell dysplasia of large and small cell type11 Progressive ductopenia

Advanced Cases Portal lymphoid aggregates mark site of disappeared bile ducts

(see Fig. 2) Cholestatic and hepatitic features result in progressive fibrosis

with: o portal–portal septum formationo additional portal–central septa9

Resulting cirrhosis:

o biliary type when cholestatic features predominateo more macronodular type when predominance of

hepatitic featureso may be any combination of two patterns

Hepatitic-type lesions appear most important for progression of fibrosis12

Special Stains and Immunohistochemistry Antimitochondrial antibodies:

o in >90% of patients1o most specific against M2 component of pyruvate

dehydrogenase complex Aberrant expression of cytokeratin 7 in hepatocytes (Fig. 3) may

be marker for:

Fig. 3: Primary biliary cirrhosis. Detail of portal tract and surrounding parenchyma. This cytokeratin 7 immunostain highlights an increase in the number of ductular structures at the portal tract periphery; expression of cytokeratin 7 in periportal hepatocytes (early stage of cholate stasis), and a few scattered, small cytokeratin 7 positive cells at some distance from the portal tract (presumed hepatic progenitor cells). (Immunostain for cytokeratin 7)

o degree of cholestasiso progression13

Diagnosis Liver biopsy:

o important in diagnosis and staging14o characteristic bile duct lesions not always seen:

due to sampling variability prevents firm histologic diagnosis

A florid bile duct lesion in PBC can be categorized as: o lymphocytico pleomorphico granulomatous cholangitis (see Fig. 1):

most diagnostic feature

Differential Diagnosis- Nodular Regeneration- Chronic Hepatitis- Drug Induced and Toxic Liver Injury- Primary Scelrosing Cholangitis

Chronic hepatitis, especially viral hepatitis C: o in viral hepatitis C, affected duct segment shows:

vacuolization and stratification of cholangiocytes

preservation of basement membrane16 no cholestatic features

Drug-induced bile duct damage: o usually ducts of smaller caliber than in PBCo clinical history comprises episode of jaundice17

Conditions characterized by bile duct damage and granulomas:























o fascioliasiso sarcoidosis:

may be difficult because may lead to: ductopenia chronic cholestatic liver disease

final diagnosis requires consideration of clinical context and laboratory data

Immune cholangitis18 or autoimmune cholangiopathy:19o clinically, biochemically, and histologically similar to

PBC, but antimitochondrial antibodies negativeo represents antimitochondrial antibody-negative

PBC:20 but reactivity to recombinant mitochondrial

antigens by immunoblotting in about 75% of such patients21

Autoimmune hepatitis–PBC overlap syndrome:22o rareo clinical, biological, and histologic features of PBC and

autoimmune hepatitis, simultaneously or sequentiallyo higher degrees of ‘hepatitic component’ of PBC, which

responds to corticosteroid therapy23

Staging/grading Several systems proposed for staging2,24–26 Most popular applicable to any vanishing bile duct disease:24

o distinguishes four stages: stage 1:

portal stage 2:

periportal stage 3:

septal fibrosis stage 4:

cirrhosis Staging in small needle biopsy specimens valuable if interpreted

with caution: o considerable variability in degree of fibrosis in different

parts of liver

Primary Scelrosing CholangitisDefinitionDisorder of the biliary tract in which there is inflammation and sclerosis of usually the medium and large ducts. About 6% of cases have small duct involvement only. Associated with inflammatory bowel disease.

Clinical Features One of most common adult chronic cholestatic liver diseases 75% cases are male Average age at diagnosis 40 years:

o sometimes children1 Typically associated with inflammatory bowel disease (70%)2–4

Gross Pathology Inflammation, strictures, and saccular dilatations in biliary system Any part of biliary tree

Histopathology Changes depend on:

o stage of diseaseo site of biopsy:

Portal Tracts Proximal to strictures:

o only features of obstruction and cholangitis Affected by primary disease:

o pleomorphic and fibrous–obliterative cholangitis5

Key lesion: o onion skin-type periductal fibrosis (Fig. 1):

Fig. 1: Primary sclerosing cholangitis. Detail of portal tract with moderately dense inflammatory infiltrate (mainly lymphocytes, some eosinophils) and concentric, lamellated, periductal fibrosis (‘onion skin’ fibrosis) around the interlobular bile duct (center). (H&E)

with degeneration and atrophy of epithelial lining:

results in disappearance of duct and eventual replacement by a fibrous scar

loss of ducts more frequent in smaller portal tracts

sometimes scars unusually prominent and resemble keloid scars6,7

in <40% of biopsy specimens5 more often medium-sized

tracts8 not pathognomonic – also in

other types of biliary disease not present in every stage of

disease If longlasting and more severe disease:

o portal fibrosis more markedo fibrous septao biliary cirrhosis

More progressive disease: o moderate to severe lymphocytic type of interface

hepatitis9 Less severe disease:

o only mild and insignificant lesions over several years10 Increased risk of developing cholangiocarcinoma:11

o strong association with dysplasia of bile duct epithelium12

Parenchymal Changes Less striking than portal changes Correspond to features of chronic cholestasis May be nodular regenerative hyperplasia before precirrhotic

stage

Special Stains and Immunohistochemistry PAS–diastase staining:

o thickening of basement membrane around damaged ducts (Fig. 2), or























Fig. 2: Primary sclerosing cholangitis. Overview of portal tract and periportal parenchyma. This portal tract shows only mild inflammation; two interlobular bile ducts show clear-cut thickening of their basement membrane, a helpful diagnostic feature. (PAS–diastase stain)

o wrinkled empty basement membranes13

Diagnosis Usually combined large and small duct PSC Small duct PSC corresponds to involvement of only

microscopically identifiable (septal and interlobular) ducts: o previously indicated by now obsolete term

pericholangitis14

Other investigations Cholangiography

Differential Diagnosis- Drug Induced and Toxic Liver Injury- Large Duct Obstruction- Primary Biliary Cirrhosis

Chronic hepatitis: o lacks:

periductal fibrosis ductopenia cholestatic features.

PBC: o may be difficult to differentiate in later stageso epithelioid granulomas:

also in about 4% of PSC cases, but not as part of granulomatous cholangitis15

o florid portal inflammation with or without lymph follicle formation favors PBC

Overlap autoimmune hepatitis and PSC described16–18 Other vanishing bile duct diseases

CHILDHOOD DISORDERS AND DISORDERS OF METABOLISMALPHA-1 ANTITRYPSIN DEFICIENCYDefinitionGenetic endoplasmic storage disease where there is mutation in the serum glycoprotein and protease inhibitor AIAT. The mutated protein (homozygous SERPINA1 Z being the most common) becomes deposited in the ER of hepatocytes, resulting in its deficiency in the serum and associated pulmonary emphysema.

Clinical FeaturesNeonatal Cholestasis

Most common liver disease in children: o seen in 11% of infants

Usually resolves without therapy by 6 months of age In ≤10%:

o prurituso cirrhosis

Poor prognosis if persistent hyperbilirubinemia beyond 1 year of age1,2

Alpha-1 Antitrypsin Deficiency In Adults3 Usually presents with pulmonary emphysema4 Liver disease:

o incidence increases with age5 Increased prevalence of hepatitis B and C viral infection:

o may contribute to hepatic complications6–8 Increased risk for:

o hepatocellular carcinoma in adult homozygous PiZ with or without cirrhosis9,10

o chronic liver disease in middle-aged or old adults with heterozygous PiZ11

Pathogenesis An endoplasmic reticulum storage disease:

o molecular abnormality of alpha-1-antitrypsin: hinders transfer through endoplasmic

reticulum: results in:

retention in endoplasmic reticulum

deficiency in plasma12

Alpha-1-antitrypsin: o serum glycoproteino protease inhibitor (Pi)o >70 allelic variants13o usual phenotype PiMo most common deficiency alleles:

PiZ: amino acid lysine substitution for

glutamic acid at position 34214 PiS

Histopathology Globular inclusions:

o in endoplasmic reticulum of periportal hepatocytes15o eosinophilico PAS–diastase positiveo 1–10μm diameter (Fig. 1)

Fig. 1: Alpha-1-antitrypsin deficiency. Detail of periportal parenchyma, showing PAS-positive inclusions of varying size in the majority of periportal hepatocytes. (PAS–diastase stain)




















o difficult to detect in infants <3 months of age

Neonatal Cholestasis Parenchymal giant cells Ductular reaction Fibrosis Paucity of interlobular bile ducts:16

o in up to 10% of cases

Alpha-1 Antitrypsin Deficiency In Adults3 Liver disease:

o varying degrees of fibrosiso cirrhosis

Special Stains and Immunohistochemistry Immunostaining with polyclonal anti-alpha-1-antitrypsin Specific monoclonal antibody:

o allows identification of PiZ gene products17 Large areas of lobular hepatic parenchyma may be

immunopositive for alpha-1-antitrypsin in PiMZ individuals

Differential Diagnosis- Neonatal Giant Cell Hepatitis- Paucity of Interlobular Bile Ducts

Immunoreactive globules in several liver diseases:19o alpha-1-antitrypsin phenotyping in plasma by

immunodiffusion or electrophoresis needed for final diagnosis

Neonatal Cholestasis May resemble extrahepatic bile duct atresia:

o need to screen for alpha-1 antitrypsin deficiency before a Kasai procedure

Genetics Alpha-1-antitrypsin:

o >70 allelic variants13o usual phenotype PiMo most common deficiency alleles:

PiZ: amino acid lysine substitution for

glutamic acid at position 34214 PiS

DISORDERS OF COPPER AND IRON METABOLISMWILSON’S DISEASEDefinitionRare autosomal recessive disorder where there is tissue injury from increased copper deposition in the liver, brain, cornea and kidneys. The mutation is localized to chromosome 13q14-21.

Clinical Features Rare Autosomal recessive:

o gene mutation on chromosome 13q14–211 After 5 years of age may present with:2

o acute hepatitiso fulminant hepatitiso chronic hepatitiso cirrhosis

Pathogenesis Tissue injury due to copper overload in:

o liver

o other organs: brain cornea kidneys

Histopathology Histologic abnormalities precede clinical appearance Early stage:

o steatosiso sometimes lipogranulomas3

Periportal hepatocytes: o may be:

strikingly abundant lipofuscin glycogen vacuoles in nuclei4

Kupffer cells: o may be laden with iron:

due to frequent acute hemolytic crises Progressive fibrosis with fine septa extending from portal tracts Sometimes portal tracts infiltrated with mononuclear

inflammatory cells: o indistinguishable from chronic hepatitis due to other

causes4–6 Untreated, progresses to cirrhosis Helpful diagnostic clues:

o steatosiso ballooned hepatocyteso glycogenated nucleio moderate to marked copper depositiono Mallory bodies in periportal hepatocyteso lymphocytic portal and interface inflammationo possibly occlusive venous lesions4

If fulminant hepatic failure: o extensive parenchymal necrosiso collapse of the reticulin frameworko nodular parenchymal regenerationo development of a cirrhotic pattern7

Electron microscopy: o characteristic mitochondrial and lysosomal changes8

Special Stains and Immunohistochemistry Cytochemical staining for copper and copper-binding protein:

o may be useful in establishing diagnosis (Fig. 1)

Fig. 1: Wilson's disease, cirrhotic stage. This rhodanine stain reveals accumulation of copper (red granules) in varying degree, most pronounced in a nodular cluster of hepatocytes (left). (Rhodanine stain)

Timm's silver stain: o appears most sensitive technique10

Stains may be negative in some stages of the disease

Diagnosis Quantitative determination of hepatic copper:



















o may be necessary for final diagnosiso can be performed on routinely processed paraffin-

embedded tissue11 Great variety of possible lesions:

o creates problems for histopathologisto consider in differential diagnosis of hepatocellular

disease at all ages, but especially if young Young and asymptomatic:

o hepatic copper levels high, but difficult to demonstrate histochemically due to diffuse distribution in hepatocyte cytoplasm

Older and signs of disease: o copper metal diffusely distributed and intralysosomal

Advanced disease: o all copper confined to lysosomes:12

more easily recognized granular pattern Cirrhotic stage:

o parenchymal nodules may vary strikingly in copper content (see Fig. 1)

Other investigations Liver biopsy:

o useful for: diagnosis monitoring

Differential Diagnosis- Steatohepatitis- Cirrhosis- Drug Induced and Toxic Liver Injury- Cholestasis- Chronic Hepatitis

Copper and metallothionein may accumulate in other diseases e.g.:

o cholestasiso Indian childhood cirrhosis

Neonatal liver usually contains high levels of copper13

Genetics Autosomal recessive:

o gene mutation on chromosome 13q14–211

Management Penicillamine or zinc acetate:

o may arrest diseaseo prevent development in siblings

IRON OVERLOADDefinitionDeposition of iron in the liver secondary to chronic anemia, blood transfusion, chronic renal failure and porphyria cutanea tarda.

Clinical Features Demonstrable iron in tissues Causes:

o genetic hemochromatosiso chronic anemia including thalassemia:

often termed secondary hemochromatosiso neonatal iron overload:

rareo blood transfusiono hemolysiso chronic renal failureo porphyria cutanea tardao ingestion of excessive amounts of iron e.g. due to:1

self-medication with iron compounds use of iron containers by South African

blacks for brewing traditional beers

Pathogenesis Neonatal iron overload:

o etiology unknowno no relationship with genetic hemochromatosiso putative environmental agents suspected to interact

with one or more factors intrinsic to developing fetal liver2

HistopathologyIron Distribution

Varies according to cause Exogenous siderosis loads Kupffer cells first (Fig. 1)

Fig. 1: Secondary siderosis. Hemosiderin (blue) is located exclusively in Kupffer cells, sparing the hepatocytes. (Perls' iron stain)

Always most pronounced in periportal hepatocytes Predominantly parenchymal in:

o hemochromatosiso neonatal iron overload:

marked hepatocellular necrosis parenchymal giant cell transformation siderosis fibrosis parenchymal nodule development3

In thalassemia and other forms of chronic anemia: o both hepatocytes and Kupffer cells store iron:

Kupffer cell and macrophage siderosis is present from early stages

o associated fibrosis and cirrhosiso in contrast with genetic hemochromatosis, often more

portal and lobular lymphocytic infiltration, due to transfusion-related viral hepatitis C4

Dense Perls-positive granules in endothelial cells in various liver diseases, including:

o acute hepatitiso alcoholic liver disease:

some hepatic siderosis common in cirrhosis most alcoholics with marked hepatic iron

overload also have genetic hemochromatosis5

Porphyria cutanea tarda: o often siderosis in periportal hepatocytes:

usually mild6 Ingestion of excessive amounts of iron:1

o combined reticuloendothelial and hepatocellular siderosis

Special Stains and ImmunohistochemistryPerls' Stain Using Acid Ferrocyanide
















Best demonstrates siderosis Gives Prussian blue reaction with ferric compounds:

o ferritino hemosiderin

Ferritin dispersed in hyaloplasm: o gives diffuse bluish tint to the cell's cytoplasm

Intense blue granules: o correspond to ferritin and hemosiderin packed

together within siderosomes (iron-laden lysosomes)7 Evaluation requires attention to:

o extent (grade or amount) of stainable iron: semiquantitative assessment of stored

tissue iron achieved in different ways: simplest system grades from 1

(minimal) to 4 (massive deposits) grades 2 and 3 indicate

intermediate amountso distribution in different cell types of portal tract and

lobule

Other investigations Chemical determination of tissue iron:

o performed on: liver tissue separated from specimen taken

for histology block deparaffinized after histopathologic

study: ensures tissular composition of

sample known8 Hepatic iron index (HII):9

o chemically measured hepatic iron concentration (μmol/g dry weight)/patient's age in years

o enables distinction of genetic hemochromatosis (HII ≥1.9) from heterozygous individuals and patients with siderosis from other causes

Chemically measured HII correlates well with histological hepatic iron index (HHII) (dividing by the age in years)10

Microscopic evaluation: o may allow blocked tissue to be preservedo can be used to quantitate when chemical iron

determination is not possible Computerized image analysis:

o correlates well with classical assayso additional technique

Differential Diagnosis- Cirrhosis- Hemochromatosis

Genetic hemochromatosis

HEMOCHROMATOSISDefinitionAutosomal recessive disorder of iron metabolism most common in Northern Europeans where there is increased iron deposition in liver, heart, pancreas and gonads. The most common mutation is missense (C282Y) of the HFE gene on chromosome 6p.

Clinical Features Autosomal recessive:

o heterozygosity rarely associated with liver damage due to iron alone1

Most common inherited disorder in white Caucasians2 Risk of hepatocellular carcinoma:

o incidence ≈15%: predominantly in males

o not prevented by removal of iron3

Pathogenesis In Northern Europe:

o >90% of cases homozygous for missense mutation (C282Y) in HFE gene on short arm of chromosome 6:

o mutation leads to dysregulation of intracellular iron homeostasis in enterocytes:

results in inappropriately high iron absorption

o role of a second mutation (H63D) in HFE gene unclear:4

C282Y mutation alone leads to mild hepatic siderosis, with exception of H63D/C282Y compound heterozygotes5

Histopathology Progressive iron accumulation in:

o livero hearto pancreaso other organs

Rate of accumulation varies: o even within same family

If Young Stainable iron in periportal hepatocytes:

o positivity in males generally greater than in females of same age

o first abnormality

With Advancing Age Progressive deposition of hemosiderin toward centrilobular area:

o usually maintains decreasing portal–central gradient Some Kupffer cells and occasional portal macrophage may

become iron positive: o overwhelmed by almost exclusive parenchymal storage

Hepatocellular iron appears as pericanalicular granules representing lysosomal storage (Fig. 1)

Fig. 1: Parenchymal siderosis in genetic hemochromatosis. Detail of lobular parenchyma showing marked parenchymal siderosis in typical lysosomal (pericanalicular) localization. There was a decreasing portal–central gradient in lobular siderosis (not shown). (Perls' iron stain)

With Progressing Siderosis Fibrosis with:

o expansion of portal tracts: carry iron-laden macrophages

o small fibrous spurs conferring spiked contour to portal tracts

o some increase in ductular profiles: usually without marked inflammation













o accumulation of granules of stainable iron by cholangiocytes of:

ductules interlobular ducts

o some reports of foci of eosinophilic or lytic hepatocellular necrosis of iron-laden hepatocytes:

often close association with clusters of macrophages:

so-called sidero-necrosis6o progressive increase in proportion of iron outside

hepatocytes versus hepatocellular iron Periportal fibrosis proceeds:

o slender periportal septa: join portal tracts progressively envelope lobules to produce

pattern characteristic for hemochromatosis of combination of:7

discrete parenchymal nodules partially preserved lobules

Further advancement: o results in diffuse micronodular pattern with portal-

based septal fibrosis: resembles secondary biliary cirrhosis

Excessive alcohol consumption: o induces shift of hemosiderin from parenchymal to:

Kupffer cells macrophages in fibrous septa7

In later stages of heavy iron overload: o occasional small areas:

without or with little parenchymal siderosis and only some Kupffer cell iron load

most often seen in established cirrhosis represent preneoplastic lesion8

After Therapeutic Phlebotomies Steady disappearance of stainable iron:

o pattern reverse of accumulation: periportal hepatocytes remain Perls'

positive longer: iron removal unmasks brown

lipofuscin-resembling pigment in hepatocytes and portal mesenchyme

o portal collagen most resistant to iron removal

Special Stains and ImmunohistochemistryPerls' Stain Using Acid Ferrocyanide

Best demonstrates siderosis Gives Prussian blue reaction with ferric compounds:

o ferritino hemosiderin

Ferritin dispersed in hyaloplasm: o gives diffuse bluish tint to the cell's cytoplasm

Intense blue granules: o correspond to ferritin and hemosiderin packed

together within siderosomes (iron-laden lysosomes)9 Evaluation requires attention to:

o extent (grade or amount) of stainable iron: semiquantitative assessment of stored

tissue iron achieved in different ways: simplest system grades from 1

(minimal) to 4 (massive deposits) grades 2 and 3 indicate

intermediate amountso distribution in different cell types of portal tract and

lobule

Diagnosis Important:

o cirrhosis can be prevented by appropriate treatment of patient and homozygous relatives, with return of life expectancy to normal3

Usually based on clinical, biochemical, genetic, and histopathologic data

Genetic diagnosis a reality:16o but phenotypic diagnosis remains important17

Unexplained small amounts of iron in hepatocytes should always raise suspicion of early stage:

o calculation of (H)HII and further serum biochemistry may help establish diagnosis

Other investigations Chemical determination of tissue iron:

o performed on: liver tissue separated from specimen taken

for histology block deparaffinized after histopathologic

study: ensures tissular composition of

sample known10 Hepatic iron index (HII):11

o chemically measured hepatic iron concentration (μmol/g dry weight)/patient's age in years

o enables distinction of genetic hemochromatosis (HII ≥1.9) from heterozygous individuals and patients with siderosis from other causes

Chemically measured HII correlates well with histological hepatic iron index (HHII) (dividing by the age in years)12

Also grading system for estimation of iron in hepatocytes, mesenchymal cells, cholangiocytes, blood vessels, and connective tissue, generating a score between 0 and 60:13

o together with HHII14 helpful in assessment of genetic hemochromatosis

Microscopic evaluation: o may allow blocked tissue to be preservedo can be used to quantitate when chemical iron

determination is not possible Computerized image analysis:

o correlates well with classical assayso additional technique

Differential Diagnosis- Iron Overload- Cirrhosis

Genetics In Northern Europe:

o >90% of cases homozygous for missense mutation (C282Y) in HFE gene on short arm of chromosome 6:

o mutation leads to dysregulation of intracellular iron homeostasis in enterocytes:

results in inappropriately high iron absorption

o role of second mutation (H63D) in HFE gene unclear4 C282Y mutation alone leads to mild hepatic

siderosis, with exception of H63D/C282Y compound heterozygotes5

Management Therapeutic phlebotomies

NODULAR HYPERPLASIA

















DefinitionNon-cirrhotic non-neoplastic nodular transformation of the liver parenchyma. It consists of nodular regenerative hyperplasia thought to be caused by portal venous thrombosis, the closely related partial nodular transformation which is limited to the perihilar region near the porta hepatis, and focal nodular hyperplasia due to arterial hyperplasia with nodular parenchymal hyperplasia and cholestasis.

Clinical Features Accompanies limited number of disorders, such as:

o congestive heart failureo Felty's syndromeo lymphoproliferative disorderso drug-induced reactions, usually associated with portal

hypertension May be:

o part of early noncirrhotic stages of primary biliary cirrhosis1

o in liver containing metastatic or primary liver tumor2 Sometimes:

o portal hypertensiono elevated:

alkaline phosphatase γ-glutamyl transpeptidase

Pathogenesis Basic lesion postulated to be portal venous thrombosis, resulting

in: o parenchymal atrophyo compensatory hyperplasia3

Arterial lesions, particularly age-associated arteriosclerosis, may contribute3

Gross Pathology Non-neoplastic nodules not delimited by fibrous septa3

Histopathology Nodules of hyperplastic hepatocytes:

o in plates > one cell thicko adjacent parenchymal cells (usually centrilobular

areas): compressed:

sometimes with perisinusoidal fibrosis

atrophico portal tracts:

generally in centero interface with other nodules:

not defined by fibrous septa: differentiates lesion from

cirrhosis (Table 1)

Table 1. Differential diagnosis of nodular regenerative hyperplasia

Disease Diffuse involvement of the liver

Septa

Nodules

Cirrhosis + + +Nodular regenerative hyperplasia

+ – +

Focal nodular hyperplasia

– + +

Generally: o no or minimal inflammationo no liver cell damage

Vascular changes: o may be subtle and inconspicuous in needle biopsies

May be aberrant ‘paraportal shunt’ vessels of noncirrhotic portal hypertension (portal phlebosclerosis):4

o in portal hypertensiono without portal hyperpressure (or possibly subclinical

stage) Nodularity better revealed on reticulin stain5

Diagnosis Histopathologic diagnosis:

o easier on surgical specimenso possible on needle biopsies

LIVER DISEASE IN PREGNANCYACUTE FATTY LIVER OF PREGNANCYDefinitionRare but serious metabolic disorder affecting primigravidae and multipara women in the last weeks of gestation characterized by fatty replacement of liver. Believed to be caused by a fatty acid transport and mitochondrial oxidation disorder of the fetus.

Clinical Features Rare Most serious pregnancy-associated disease Develops in last weeks of gestation Both primigravidae and multipara Unexplained jaundice in late pregnancy Usually does not recur in subsequent pregnancies1

Pathogenesis Fatty acid transport and mitochondrial oxidation (FATMO)

disorder of fetus2

Gross Pathology Yellow Frequently small due to substantial loss of parenchyma

Histopathology Microvesicular steatosis:

o most characteristic featureo usually involves entire liver lobuleo sometimes spares narrow periportal rim of

hepatocytes (Fig. 1)




http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70835-X#bib5


http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675(06)70835-X#tbl1







Fig. 1: Acute fatty liver of pregnancy. Detail of lobular parenchyma characterized by microvesicular steatosis and a small number of lymphocytes. (H&E)

Fibrin thrombi: o occasionally in hepatic sinusoids

Sometimes: o cholestasiso hepatocellular necrosiso extramedullary hematopoiesiso giant mitochondria3,4

Diagnosis In routinely stained sections:

o hepatocytes containing very fine fat droplets <1μm diameter:

may not be recognized as steatotic may appear as ballooned hepatocytes:

mimic hydropic swelling of liver cells in acute viral hepatitis:

may cause problems of diagnosis in the 10–20% of cases with a lymphoplasmacytic infiltrate and acidophil bodies3,5

Histochemical fat stains on frozen section:4o make diagnosis clear

Differential Diagnosis- Toxemia of Pregnancy- Drug Induced and Toxic Liver Injury- Steatohepatitis- Acute Hepatitis

Management Termination of pregnancy Supportive care for hepatic encephalopathy and extrahepatic

complications

Prognosis Has improved dramatically over past couple of decades

TOXEMIA OF PREGNANCY

Definition

Complication of pregnancy characterized by hypertension with proteinuria, peripheral edema and coagulation abnormalities (pre-eclampsia) and convulsions and coma (eclampsia). HELLP syndrome (hemolysis, elevated liver enzymes and low platelet count) can also occur in pre-eclamptic women.

Clinical Features 5% of pregnancies:

o incidence increased in: primigravidae acute fatty liver of pregnancy1

Generally during third trimester Hypertension induced or aggravated by pregnancy Association with:

o proteinuriao peripheral edema

Occasional coagulation abnormalities May be convulsions and coma2 If severe:

o hepatocellular dysfunction with elevated: serum transaminases alkaline phosphatase

o may lead to: liver failure two rare often fatal complications:

liver rupture preceded by subcapsular hematoma

infarction of liver3

Gross Pathology Diffuse, fine or blotchy hemorrhages over capsule and on cut

surface2,3 Intravascular coagulation due to endothelial injury and disruption

Histopathology Fibrin thrombi in:

o portal vesselso periportal sinusoids

Hemorrhage Hepatocellular necrosis

Special Stains and Immunohistochemistry Fibrin identified by:

o phosphotungstic acid–hematoxylin (PTAH) stainingo immunohistochemistry

Differential Diagnosis- Drug Induced and Toxic Liver Injury- Acute Fatty Liver of Pregnancy

LIVER INVOLVEMENT IN OTHER ORGAN SYSTEMS AND SYSTEMIC DISEASESGRANULOMASDefinitionGranulomas are seen in 3-15% of liver biopsies. Some causes include sarcoidosis, primary biliary cirrhosis, infections such as Q-fever, tuberculosis and fungi.

Clinical FeaturesEpithelioid Granulomas

In 3–15% of liver biopsies1,2Sarcoidosis

Incidence in established sarcoid 21–79% If clinical evidence of hepatic disease:

o granulomatous inflammation in 100% of biopsies3

PathogenesisEpithelioid Granulomas












Diverse etiologies4 Cause unknown in up to 50% of cases5

Fibrin-ring Granulomas Occur in:

o Q fevero allopurinol hypersensitivityo cytomegalovirus infectiono Epstein–Barr virus infectiono leishmaniasiso toxoplasmosiso hepatitis Ao Hodgkin's lymphomao giant cell arteritiso systemic lupus

May be nonspecific reaction to liver injury6

Lipogranuloma Focal response to rupture of lipid-laden hepatocytes

HistopathologyEpithelioid GranulomasSarcoidosis

Three broad categories of abnormalities besides granulomatous inflammation:3

o cholestatic (58%)o necroinflammatory (41%)o vascular (20%)

Histologic mimics of several other disorders, including: o primary biliary cirrhosiso primary sclerosing cholangitiso drug-induced liver diseaseo bile duct obstructiono viral hepatitis

Hepatic fibrosis (in 21%), including 6% with cirrhosis: o sometimes progressive liver disease

Epithelioid granulomas: o may be differing ageso typically:

greatest frequency in portal and periportal areas, often in clusters

heal with fibrosis: so often in same biopsy varying

numbers and degrees of: epithelioid cells inflammation giant cells scarring

o sometimes masses of granulomas and fibrosis (sarcoidoma):

raise clinical suspicion of neoplasm3Fibrin-ring Granulomas

Distinctive ring pattern Fibrin deposited circumferentially within or at margin Composed of:

o epithelioid cellso giant cellso neutrophilso central fat vacuole (Fig. 1)

Fig. 1: Q fever. Detail of lobular parenchyma with some steatosis and two fibrin ring granulomas. The granuloma is composed of a central fat vacuole, a layer of histiocytes and lymphocytes, a fibrin ring, and additional accumulation of inflammatory cells. (H&E)

Lipogranuloma Focal lesion May be:

o abundant: especially in alcohol-induced steatosis

o confluent Contains:

o macrophageso occasional lymphocyteso eosinophilso sometimes giant cells (Fig. 2)

Fig. 2: Hepatic steatosis in patient with alcohol abuse. The picture shows a mixture of macrovesicular and microvesicular steatosis and a lipogranuloma (upper right corner). (H&E)

Special Stains and ImmunohistochemistryEpithelioid Granulomas

Stains for microorganisms: o Ziehl–Neelseno silver methenamine for fungio immunostaining

Polarizing microscopy for inclusions X-ray microanalysis e.g. for:

o goldo bariumo silicon4

DiagnosisEpithelioid Granulomas

Careful histologic evaluation of: o granulomaso associated changes e.g.:

hepatitis bilirubin stasis bile duct damage












Step sections: o often helpfulo essential when suspected but not in initial sections

Special techniques may be helpful4

Etiologic Diagnosis Made with clinical context in mind

Four Groups4 See cause on microscopic examination e.g.:

o ova of schistosomao demonstrable mycobacteria after appropriate staining

Know cause or diagnosis: o requires knowledge of clinical data e.g.

primary biliary cirrhosis if: granulomas and lymphoid

infiltrates adjacent to injured bile ducts in middle-aged female with:

pruritus raised serum alkaline

phosphatase antimitochondrial

antibodies4 Suspect diagnosis e.g.:

o granulomas with many eosinophils suggest: drug-induced lesions, or parasitosis.

Cause unknown: o largest groupo consider tuberculosis

Fibrin-ring Granulomas May require serial sections7

Lipogranuloma May require serial sections to:

o identify central fat globuleo differentiate from other forms of granuloma

Differential Diagnosis- Drug Induced and Toxic Liver Injury- Cholestasis- Lymphoma

Epithelioid GranulomasSarcoidosis

Primary biliary cirrhosis: o differentiation can be difficult to because:

both may lead to: portal granulomas bile duct injury and destruction ductopenia chronic cholestasis9,10

may coexist11 Sometimes predominantly portal hypertension:12

o due to portal granulomas and fibrosis13o final diagnosis cannot be made from liver biopsy alone

due to multiplicity of mimicking granulomatous diseases

AMYLOIDOSIS AND LIGHT CHAIN DEPOSITION DISEASEDefinition

Perisinusoidal and portal deposition of homogeneous material (amyloid and lambda and kappa light chains) in the liver.

Clinical FeaturesAmyloidosis

Systemic amyloidosis: o commonly involves livero rarely clinically evident hepatic disease

Light Chain Deposition Disease Exceptionally:

o coexists with amyloido intrahepatic cholestasis1

HistopathologyAmyloidosis

Amyloid: o homogeneous eosinophilic extracellular material (Fig.

1)

Fig. 1: Amyloidosis. Detail of lobular parenchyma with massive amyloid deposition in the space of Disse and corresponding marked atrophy of liver cell plates. (H&E)

o Amyloid deposition:o usually:

in hepatic artery branches along sinusoids in space of Disse:

leads to: atrophy of liver cell plates narrowing of sinusoids:

occasionally results in: intrahepatic cholestasis portal hypertension2,3

o much more rarely globular deposits4

Light Chain Deposition Disease Hepatic involvement:

o homogeneous perisinusoidal and portal depositions: resemble amyloid

o usually renal symptoms

Special Stains and ImmunohistochemistryAmyloidosis

Amyloid: o apple green birefringence after positive Congo red

staining

Light Chain Deposition Disease Light chain deposits:

o no green birefringence after Congo red staining Immunohistochemical staining for kappa and lambda light chains:

o permits identificationo usually kappa (Fig. 2)

















Fig. 2: Light chain deposition disease. Detail of lobular parenchyma with kappa chain deposition in the space of Disse. (Immunostain for kappa light chain)

DiagnosisAmyloidosis

Primary myeloma-associated (AL) amyloidosis vs reactive (AA) amyloidosis:

o cannot be reliably distinguished by topographic distribution pattern of deposits

o AL amyloid: Congo red positive if potassium

permanganate treatment before Congo red staining5

positive in light chain immunostains

Differential Diagnosis- Cirrhosis- Alpha 1 Antitrypsin Deficiency

LIVER PATHOLOGY IN ORGAN TRANSPLANTATIONLIVER TRANSPLANTDefinitionHepatic pathology associated with transplantation includes preservation injury, hyperacute, acute and chronic allograft rejection. Diseases such as hepatitis B, C, PBC, PSC, autoimmune hepatitis and tumors can also recur in the allograft.

Clinical FeaturesPreservation injury

Appears early: o first 2 weeks post transplant

Regresses spontaneously over several weeks1Humoral Rejection

Rare Within first few hours after transplantation Results in coagulative and hemorrhagic necrosis in a few days

Acute Rejection Most common form of rejection Mean incidence ≈50%2 Generally within first 3 weeks after transplantation:

o median onset 7–10 days3o late presentations usually related to decreased

immunosuppression4Chronic Rejection

History of acute cellular rejection Progressive cholestasis

Other Complications Following TransplantationBile Duct Stricture

At site of anastomosis or elsewhereHepatic Artery Thrombosis

Alone or in combination with portal vein thrombosis More common in children Results in infarction

Infections Common

Drug-induced Injury Several drugs in immunosuppressive therapeutic regimen capable

of causing hepatic damage May be difficult to incriminate a specific drug due to numerous

confounding featuresRecurrent Disease

Risk highest if: o neoplastico chronic viral hepatitis

HCV Recurrence Severe progressive cholestatic syndrome:

o incidence 2–10%Primary Biliary Cirrhosis

Antimitochondrial antibodies: o persisto do not correlate with disease recurrence

Neoplastic Disease Malignancies after liver transplantation comprise:

o hepatocellular carcinoma: recurrent5 or de novo6,7 mainly in recipients transplanted for chronic

viral hepatitis B and Co post-transplant lymphoproliferative disease

mostly nodal and extranodal B-cell lymphoma

PathogenesisDiseases Affecting Grafted Liver8

Diseases affecting nontransplanted livers Preservation (ischemia/reperfusion) injury Allograft rejection Complications e.g.:

o surgical mishapo hepatic artery thrombosiso portal vein thrombosiso bile duct problems such as:

dehiscence leaks necrosis strictures concrement formation infection

Drug reactions Opportunistic infections Recurrent disease Post-transplant lymphoproliferative disorder

Preservation injury Nonimmunologic graft damage resulting from:

o harvestingo ischemic preservationo transportationo reperfusion9

Allograft Rejection Caused by immunologic reaction of host2,10–13 May be:

o humoral:o acute:o chronic (ductopenic)14,15

Humoral Rejection Rare Preformed or subsequently formed antibodies:

o to an ABO blood group-incompatible donor16o react with graft vasculature















o cause endothelial damage and thrombosisAcute Rejection

Cell-mediated immune reaction directed at: o bile duct epitheliumo endothelium of portal and centrilobular veins15

Chronic Rejection Immunologic injury that:

o usually evolves from severe or persistent acute cellular rejection

o results in potentially irreversible damage to: bile ducts arteries terminal hepatic veins surrounding parenchyma14,17

Other Complications Following TransplantationInfections

Consequence of immunosuppressive therapy Wide range of bacterial, viral, fungal, and protozoal pathogens

including: o cytomegalovirus and Epstein–Barr virus infectionso sepsis due to Gram-negative bacilli

Recurrent DiseaseRecurrent Hepatitis B

Fibrosing cholestatic hepatitis:18o associated with high viral loado occurs in other types of immunodeficiency states19

Co-infection by hepatitis B and D virus as primary disease: o may attenuate HBV recurrence post transplantation20

HCV Recurrence Severe progressive cholestatic syndrome:

o apparently due to direct viral cytopathic effect by high viral load21,22

Neoplastic Disease Post-transplant lymphoproliferative disease:

o complication of immunosuppressive treatment

HistopathologyIdentification of underlying donor liver disease at allograft procurement

Frozen sectionContraindications To Use As Allograft

Marked macrovesicular steatosis:23,24o risk of primary graft dysfunction25o semiquantitative parenchymal involvement:

absent mild (<30%) moderate (30–60%) marked (>60%):24,25

Primary or metastatic malignant tumorPreservation injury

Surgical necroses: o quite commono often observed in any surgical specimen26o clusters of neutrophils and scattered acidophil bodies

(Fig. 1)

Fig. 1: Surgical necroses consist of focal necrosis of hepatocytes and accumulation of clusters of neutrophil polymorphs. Originally described in specimens taken at the end of abdominal surgical interventions, they are now also recognized as a marker of ‘preservation damage’ in donor livers after revascularization during liver transplantation. (H&E)

Functional cholestasis: o bilirubin stasis in:

hepatocytes canaliculi27

o distinguish from cholestasis associated with: acute rejection drug toxicity hepatitis bile duct obstruction sepsis

Hepatocellular ballooning: o diffuse or centrilobular28,29o by itself, does not carry a bad prognosis29o possibly associated with bilirubin stasis

Centrilobular hepatocyte necrosis: o a more severe preservation injuryo due to hypoperfusiono a differential diagnostic problem because confluent

necrosis in: vascular complications drug-induced injury as poor prognostic sign in acute and chronic

allograft rejection30Acute Rejection (Fig. 2)

Fig. 2: Acute (cellular) rejection of liver allograft. Detail of portal tract showing dense mixed infiltrate (including lymphocytes, more immature lymphoid type cells, and eosinophils), mild endotheliitis (from center to lower right), and bile duct involvement (center left and center bottom). (H&E) (Courtesy of Prof. T Roskams, Leuven)

Triad of: o portal infiltrationo bile duct damage:o usually endotheliitis




















Portal Infiltration Mixture of inflammatory cells:

o small lymphocytes predominateo larger lymphoid type cellso immunoblastso macrophageso plasma cellso neutrophilso eosinophils:

sometimes abundant and a helpful diagnostic feature31

o typically expands portal tracto may be focal and unevenly distributedo occasionally:

extends beyond limits of portal tract leads to portal–portal bridging necrosis32

Bile Duct Damage Bile ducts infiltrated by:

o lymphocyteso lymphoid-type cells (lymphocytic cholangitis)

Bile duct epithelial damage reflected in: o anisonucleosiso cytoplasmic vacuolizationo areas of cell stratification or occasional dropouto irregularities in duct outlines

Endotheliitis Portal or central veins Supraendothelial and subendothelial lymphocytes Endothelial damage Lifting off of endothelium from underlying layers Indicative of severe cellular rejection of:

o centrilobular veinso necrosis of centrilobular hepatocytes

Periportal extension of portal inflammatory infiltrate33A Less Frequent Form Of Cellular Rejection

Endothelial predominance: o isolated central venulitis in adult and pediatric liver

allograft recipients34,35o may result in:

perivenular fibrosis a veno-occlusive syndrome36

Grading Systems Several proposed:2

o to predict unfavorable clinical outcomeso consensus document33

Additional features less consistently present: o bilirubin stasiso some lobular inflammatory mononuclear infiltrateo if severe rejection:

centrilobular confluent parenchymal necrosis

Chronic Rejection (Fig. 3)

Fig. 3: Chronic ‘ductopenic’

rejection of liver allograft. Portal tract without bile duct and very sparse lymphocytic infiltration. (H&E)

Minimal diagnostic criteria: o bile duct atrophy/pyknosis:

affects majority of bile ducts with or without bile duct loss

o convincing foam cell obliterative arteriopathy, oro bile duct loss of >50% of portal tracts

Arteries with pathognomonic changes: o predominate in hilar regiono rarely in needle biopsy specimens

Considerable significance placed on damage and loss of small bile ducts

Changes mainly affect: o portal tracts:

loss of small bile ducts small branches of hepatic artery

o centrilobular areasEarly Bile Duct Changes

Uneven nuclear spacing Nuclear:

o enlargemento hyperchromasia

Interrupted epithelial lining of ductsEarly Arterial Lesions

Accumulation of subintimal, medial, and adventitial foamy macrophages

Late Bile Duct And Arterial Damage Mainly evaluated by extent of loss:

o bile duct loss when <80% of portal tracts contain bile ducts

o arterial loss when <77% of portal tracts contain hepatic artery branches17

Early lesions In Centrilobular Area Subendothelial and perivenular mononuclear inflammation of

centrilobular vein Centrilobular hepatocyte dropout Pigment-laden macrophages Mild perivenular fibrosis

‘Transitional Hepatitis’ Sometimes difficult to distinguish from viral hepatitis May occur during evolution to late stages37

Late Chronic Rejection Severe (bridging) perivenular fibrosis At least focal central–central or central–portal bridging Occasional obliteration of terminal hepatic venules

Other complications following transplantationBile Duct Strictures

Histologic features of any biliary obstructionDrug-induced Injury

Azathioprine: o associated with:

sinusoidal congestion centrilobular necrosis38

Ciclosporin: o may cause:

canalicular bilirubin stasis hepatocyte ballooning vacuolization of bile duct epithelial cells39

Recurrent Disease Some have histopathologic features that overlap with those in:

o rejectiono post-transplant biliary stricture

Recurrent Hepatitis B















May cause: o acute and chronic hepatitiso cirrhosiso minimal histologic changes (carrier state)o in a minority of cases, fibrosing cholestatic hepatitis:18

occurs early (before 150 days)40 rapidly progressive graft dysfunction characterized by:

perisinusoidal bands of fibrosis around plates of ductular-type epithelium

prominent bilirubin stasis ground glass hepatocytes hepatocellular ballooning with

cell loss mild mixed inflammatory

reaction18HCV Recurrence

As defined by histologic injury almost universal Sometimes severe graft injury resulting in graft loss20,41,42

Primary Biliary Cirrhosis Liver biopsy:

o gold standard for diagnosis of recurrence:43 most helpful features:

florid bile duct lesions epithelioid granulomas

granulomatous cholangitis also observed in chronic viral hepatitis C44

less helpful features that may occur in chronic hepatitis C and allograft rejection:

portal lymphoid aggregates ductopenia

other useful features: ductular reaction progressive cholate stasis

(including copper deposition) suggested early marker:

plasma cells in portal infiltrate45Primary Sclerosing Cholangitis46

Requires well-defined cholangiographic and histologic criteria42 Features resemble those of complications of transplant procedure

Autoimmune Hepatitis Based on clinical, biochemical, serologic, and histologic criteria:43

o portal and periportal inflammation (interface hepatitis) containing plasma cells47

Diagnosis Percutaneous liver biopsies:

o obtained when symptoms of deterioration of liver function

Protocol biopsies: o biopsies obtained on planned schedule irrespective of

liver chemistry48,49 Fine needle aspiration biopsy:

o may be adequate in experienced hands50 Several pathologic conditions may coexist in liver allograft such as:

o drug toxicityo viral hepatitiso disease recurrenceo rejection

Preservation injury Time zero biopsies:

o for evaluation

o obtained at transplantation directly after revascularization of graft51

Chronic Rejection Diagnosis based on combination of clinical, radiological,

laboratory, and histopathologic findings Defining features not uniformly present:

o bile duct loss can occur without arteriopathyo arteriopathy can occur without bile duct losso severe (bridging) centrilobular fibrosis may be present

without significant bile duct loss or obliterative arteriopathy

o may be late features of one component (e.g. bile duct loss) and early features of another component (e.g. perivenular necrosis)17

Working formulation for histopathologic staging and reporting of chronic liver allograft rejection proposed:

o early chronic rejection: if no more than one of the target structures

shows late changeso late chronic rejection:

at least two or more target structures show late changes

Differential Diagnosis- Cholestasis- Chronic Hepatitis- Acute Hepatitis

Chronic Rejection Other causes of ductal injury and loss including:

o biliary tract obstructiono hepatic artery thrombosis17

HCV Recurrence Differentiation from cellular rejection may require:

o sequential biopsieso grading of lesions to document progressive

appearance of hepatitis C features

GRAFT VERSUS HOST DISEASE

DefinitionLiver damage as a complication of bone marrow transplantation. Divided into acute and chronic forms.

Clinical FeaturesAcute Hepatic GVHD

<90 days after bone marrow transplantationChronic GVHD

Usually preceded by acute GVHD May be de novo:

o ≈25% of cases >3 months after bone marrow transplantation

Pathogenesis Complication of bone marrow transplantation1,2



















HistopathologyAcute Hepatic GVHD

Cholestasis Bile duct damage:

o affected ducts: irregular profile epithelial atypia with:

nuclear pleomorphism cytoplasmic vacuolation cell necrosis

o may be duct destructiono lymphocytic infiltration of duct epitheliumo mild portal inflammation

Early biopsies (<35 days): o less bile duct damageo marked hepatocellular apoptosis3

Other lesions: o endotheliitiso siderosiso veno-occlusive disease4

Chronic GVHD Similar to acute GVHD, but more severe Dense portal infiltration:

o sometimes: periportal extension interface hepatitis

Lobular changes include: o bilirubin stasiso apoptotic bodies

When advanced: o ductopenia5o cholate stasiso progressive periportal fibrosiso cirrhosis

Differential Diagnosis- Acute Hepatitis- Drug Induced and Toxic Liver Disease- Cholestasis

Acute Hepatic GVHD Picture in early biopsies (<35 days) easily confused with viral

hepatitis C

ECHINOCOCCUS CYST (Hydatid Cyst)DefinitionInfection of the liver by the larval or cystic stage of echinococcus tapeworms. The most common is E. granulosus, but the most aggressive is E. multilocularis.

Clinical FeaturesEchinococcus granulosus

Most frequent cause of echinococcus cysts: Commonly communication with biliary tract and superimposed

infection1 May rupture:

o into peritoneal cavity and result in: fatal anaphylactic reaction formation of innumerable small granulomas

grossly resembling peritoneal tuberculosis: fragments of germinal

membrane or scolices in center points indicate diagnosis

o inside gallbladdero through diaphragm into pleural space and lung

Echinococcus multilocularis Compared with E. granulosus:

o less commono more aggressive clinical disease

Pathogenesis Result of hydatid disease caused by larval or cystic stage of

Echinococcus tapewormsEchinococcus granulosus

Adults in dogs and jackals in all continents2 Ingested eggs hatch into larval oncospheres, which enter liver by

portal vein

Gross PathologyEchinococcus granulosus

Hepatic cyst (Fig. 1):

Fig. 1: Echinococcosis of the liver.

o one or more in 75% of infected individualso slow growtho typically sphericalo may be >30cm diametero usually right lobeo may be multiple, involving all lobes3,4

Echinococcus multilocularis Multilocular, necrotic, cystic cavities:

o contain thick pasty materialo not surrounded by a fibrous wall

HistopathologyEchinococcus granulosus

Cyst wall: o outer chitinous (or fibrous laminar) layero inner germinal layero may be surrounding pericyst layer of either:

granulation tissue fibrous capsule:

calcification signifies cyst is dead Adjacent liver parenchyma:

o often: pressure atrophy portal infiltrate:

eosinophils may be prominent Viable cyst:

o filled with colorless fluid: contains:

daughter cysts brood capsules with scolices:

scolices easily identified:










after macerating portion of germinal layer in saline

characteristic hooklets 20–40μm long

Sometimes daughter cysts outside chitinous layer: o i.e. extracapsular or satellite cysts5

Echinococcus multilocularis Irregular cysts:

o may be surrounding: granulomatous reaction containing

neutrophils and eosinophils rim of:

necrosis fibrosis focal calcification6

Laminated membrane: o clearly visualized by PAS staino often fragmented

No: o nucleated germinal membraneo protoscolices

Differential Diagnosis- Liver Abscess- Metastatic Tumors- Mucous Cystadenoma

ABSCESS

DefinitionHepatic abscesses are due to the following in descending order: biliary obstruction and infection, systemic bacteremia, direct extension from contiguous infection, trauma and pylephlebitis. Tuberculous and anaerobic infections have been increasing while amebic and culture negative cases have been decreasing.

Clinical Features Mortality rate 10–20%1,2 In US usually:

o older adults, oro HIV-infected or other immunocompromised young

individualsAmebic Abscess

Usually adult3,4

Pathogenesis In past usually:

o amebic, oro secondary to pylephlebitis

Today in US: o usually due to enteric bacteria

o increasing number of tuberculous ‘abscesses’5,6 in immunocompromised

Predisposing factors, in descending order of frequency: o biliary tract obstruction/infectiono systemic bacteremiao direct extension from contiguous infectiono penetrating or nonpenetrating traumao pylephlebitis7,8

Specific causes: o secondary bacterial infection of metastatic tumor

noduleso inflammatory bowel disease9o pancreatitis10o chemotherapy11o dental disease12

Gross Pathology Size varies (Fig. 1)

Fig. 1: Large liver abscess surrounded by a thick fibrous wall.

May be multiple: o ≈50% of pyogenic abscesseso ≈25% of amebic abscesses13

Communication between abscess and intrahepatic biliary system slightly <50% of cases14

Amebic Abscess Usually:

o singleo right sidedo close to liver dome15 (Fig. 2)

Fig. 2: Amebic abscesses occupying most of the right lobe of the liver. Three distinct lobules are seen. (Courtesy of Dr RA Cooke, Brisbane, Australia; from Cooke RA, Stewart B: Colour Atlas of Anatomical Pathology. Edinburgh, Churchill Livingstone, 2004).

Greater tendency for multicentricity if immunocompromised Necrotic center:

o usually contains odorless, pasty, chocolate brown fluid May be:



















o extension and perforation into: pleuropulmonary structures subphrenic space peritoneal cavity less commonly:

pericardial sac bile ducts kidney mediastinum chest wall abdominal wall flank16

HistopathologyAmebic Abscess

Mainly necrotic material Few if any neutrophils Surrounding layer of:

o fibrino macrophageso lymphocyteso few fibroblasts

Wall thinner than that of bacterial liver abscess Usually clusters of amebae:

o extensive search may be necessary May be:

o superinfection by bacteria

Other investigations Anaerobic culture10 Diagnostic imaging:

o ultrasonographyo CTo MRIo angiographyo useful in:

identifying hepatic abscesses distinction from necrotic tumors

Differential Diagnosis- Acute Hepatitis- Metastatic Tumors

Management Includes:

o antibiotics: rarely effective if sole treatment

o aspiration: rarely effective if sole treatment

o drainageo excision



non neoplastic liver

Documents

o common o

o uncommon o

o mild o moderate

selflimited hepatitis

o o nuclear pyknosis

o anisokaryosis

adults o

helpful o