Cellular Pathology

Histopathology Lab #2

(web)

Paul Hanna Jan 2018

Clinical History:

• a necropsy was performed on an aged cat

• the gross pathological changes included:

widespread subcutaneous edema

ascites

hydrothorax

multiple, pale, wedge-shaped lesions in kidneys

Slide #91

• tissues were sent to AVC for histopathologic examination

Well demarcated pale wedge shaped lesion in renal cortex; with base of

the wedge near the capsule and apex near cortico-medullary junction.

Note – size of the infarct

depends on caliber of vessel

that becomes obstructed

Normal kidney, gross sagittal section, cat (above left) and normal histology of the kidney

Well demarcated pale

wedge shaped lesion in

renal cortex; with base

of the wedge near the

capsule and apex near

cortico-medullary

junction.

Slide #91

Within the affected

area the basic

architectural

arrangement of the

glomeruli and tubules

is apparent however

the cells resemble an

eosinophilic shadow

(ghost-like remnant)

of the original cells.

Surrounding layer of

inflammatory cells;

most of which are

degenerate.

Within the affected

necrotic area the

basic architectural

arrangement of the

glomeruli and tubules

is apparent however

the cells resemble an

eosinophilic shadow

(ghost-like remnant)

of the original cells.

Surrounding layer of

inflammatory cells;

most of which are

degenerate.

Within the affected

necrotic area the basic

architectural

arrangement of the

glomeruli and tubules

is apparent however

the cells resemble an

eosinophilic shadow

(ghost-like remnant) of

the original cells.

Most nuclei are

inapparent (karyolysis)

Surrounding layer of

inflammatory cells;

most of which are

degenerate.

Within the affected

necrotic area the basic

architectural arrangement

of the glomeruli and

tubules is apparent

however the cells

resemble an eosinophilic

shadow (ghost-like

remnant) of the original

cells. Most nuclei are

inapparent (karyolysis)

Slide #91

Morphologic Diagnosis: Renal infarct (locally extensive necrosis of the renal cortex)

Comment:

• an interlobar or arcuate renal artery was obstructed by a thrombus / thromboembolus resulting in ischemia to the renal parenchyma and subsequently coagulation necrosis.

• layer of inflammatory cells at the margin of the infarct is a response to the dead tissue.

Description:

• on low-power this section of kidney contains an irregular, wedge-shaped pale eosinophilic area which has a basophilic border.

• the apex of this triangular area is within the medulla, while the base is approximately 1-2 mm from the capsular surface.

• the inner material is composed of ghost-like remnants of the renal parenchyma (coagulation necrosis of tubules, glomeruli, etc) and the whole area is surrounded by a thick layer of inflammatory cell debris.

• there is an increase of fibrous connective tissue and some inflammatory cells within the interstitium of the remainder of the renal cortex (pre-existing nephritis).

Case #95

History:

• three-year-old, DLH, female, cat

• ear margins turning dark color over last few weeks (February)

Note, necrotic ear tips (above) and sloughing of

necrotic ear tip on cat (right) with some “raw”

(granulation tissue) along the remaining margin.

Base of pinna

normal tissue Necrotic

tip of ear

Layer of

inflammation

separating

viable from

necrotic tissue

Base of pinna – normal tissue

Base of pinna – normal tissue

Case #95

Necrotic

tip of ear

Layer of

inflammation

separating

viable from

necrotic tissue

Case #95

Necrotic

tip of ear

Layer of

inflammation

separating

viable from

necrotic tissue

The affected region appears as an acidophilic shadow (ghost-like remnant) of the normal tissue /

cells (ie architecture intact but acidophilia and karyolysis). Note – melanin pigment has persisted.

The affected region appears as an acidophilic shadow (ghost-like remnant) of the normal tissue /

cells (ie architecture intact but acidophilia and karyolysis). Note – melanin pigment has persisted.

Case #95

Description:

• on low-power examination a section of pinna shows hypereosinophilia of the peripheral half of

the section with a zone of basophilia at the junctional zone.

• on higher magnification, the affected region appears as an acidophilic shadow (ghost-like

remnant) of the normal tissue / cells (ie architecture intact but acidophilia and karyolysis).

• the basophilic zone, between viable and necrotic tissue, consists of inflammatory cell debris.

Morphologic Diagnosis: Locally-extensive necrosis (infarction) of the pinna

Comment:

• lesion is consistent with frostbite (ie dry gangrene = coagulation necrosis of an extremity).

• the cold temperature caused vasoconstriction (ie reduced blood supply to the ear tip) which

resulted in ischemic coagulative necrosis (= infarction) of the ear tip.

Clinical History:

• sudden death in a 1-month-old lamb.

• at necropsy the lamb was in good body condition, the majority of skeletal muscles

& left ventricle wall had numerous irregular patchy areas of white discoloration.

• a moderate amount of edematous fluid was present within the thoracic and

abdominal cavities as well as in ventral dependent areas (ie subcutaneous edema

of limbs and ventral abdominal wall).

Case #60

Gross images from a similar case

with skeletal muscle lesions (above)

and myocardial lesions (right).

Skeletal muscle – longitudinal sections Skeletal muscle – cross sections

Three segments of

skeletal muscle from

affected lamb

Case #60

Case #60

note –

fragmentation

and

mineralization

of necrotic

myocytes

Inflammatory

cells (mostly

macrophages)

removing

necrotic cells.

Fragmented

hyalined

myofiber

Fragmented mineralized myofiber

(mineralization is recognized as basophilic

granularity and clumps on H&E staining)

Inflammatory cells (mostly

macrophages) removing

necrotic material.

Case #60

Description:

• the skeletal muscle changes vary in the 3 sections of slide #60 in regards to severity.

• severe lesions are characteristic of coagulation necrosis; ie loss of myofibers with many

remaining myofibers showing fragmentation, intensely eosinophilic staining of cytoplasm

(hyalinization & loss of striations) and often pyknotic nuclei with aggregates of basophilic,

granular material (mineralization).

• there are frequently many mononuclear cells around myofibers (ie phagocytosis by

macrophages).

• if you examine the slide you will note in some areas there are many clusters of enlarged

myofiber nuclei which are indicative of regeneration myofibers.

Comment:

• the history and lesions are characteristic of nutritional myopathy (“white muscle disease”) due

to deficiency of selenium &/or vitamin E.

Morphologic Diagnosis: Myopathy, necrotizing, severe with mineralization

Signalment:

• one-year-old male sheep.

Clinical History:

• brief history of neurological signs prior to euthanasia.

• at necropsy, a large abscess was found in the pituitary fossa and a suppurative

exudate was present in the meninges of the brainstem.

• tissues were taken for histopathology including the pituitary gland.

Case #19

Thick dry pus (purulent / suppurative exudate) filling pituitary

fossa (sella turcica). Note if the pus was less thick (ie more

liquid) pus it would have oozed out of this area and we would

not be able to capture it in a histologic section.

Acidophilic regions are areas of thick dry pus (liquefactive necrosis)

with surrounding basophlic zones of degenerate inflammatory cells

(predominately neutrophils). Note if it was less thick (ie more liquid) pus

it would have oozed out of the tissue and these spaces would be empty.

Acidophilic regions are areas of liquefactive

necrosis. On gross exam this would be a

thick purulent / suppurative exudate (pus)

Surrounding basophlic zones of

degenerate inflammatory cells

(predominately neutrophils)

Areas of viable

pituitary gland

Acidophilic region of liquefactive necrosis

(mostly necrotic neutrophils). Note complete

loss of cellular detail (ie amorphous)

Surrounding basophlic zone of degenerating

neutrophils which eventually “liquify” to form the bulk

of the necrotic material

Acidophilic region of liquefactive necrosis

(mostly necrotic neutrophils admixed with

bacteria). Note complete loss of cellular

detail (ie amorphous)

Surrounding basophlic zone of

degenerating neutrophils which

eventually “liquify” to form the bulk of

the necrotic material

Fibrous capsule beginning to

form in attempt to “wall off”

this inflammatory process

Myriads (massive numbers) of bacteria are admixed among the necrotic

material. They aren’t resolved well in this H&E stain, however a Gram

stain of this section would make them more distinctive)

Zone of degenerating neutrophils which

eventually “liquify” to form the bulk of the

necrotic material (lots of enzymatic digestion)

Morphologic Features:

• the majority of normal pituitary tissue is destroyed by the inflammatory reaction.

• the reaction consists of multifocal to coalescing areas of amorphous eosinophilic material

(liquefactive necrosis) which are surrounded by layers of inflammatory cells (mostly

degenerate neutrophils) and then bands of fibrous connective tissue.

• the inflammatory cells are predominately neutrophils with fewer macrophages, lymphocytes

and plasma cells.

• large numbers of bacteria are admixed with the inflammatory cell debris.

Case #19

Morphologic Dx: Pituitary abscess

(hypophysitis, suppurative, locally extensive, chronic, severe)

Comment:

• neurologic signs were likely due to accompanying meningitis.

• Trueperella pyogenes is a frequent cause of abscesses, mastitis & pneumonia in farm animals

• bacteria reach the pituitary hematogenously (via blood stream) or locally from the oropharynx.