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Diseases of the Skin
(Noel C. Santos, M.D.)
DEFINITION OF TERMS:
Macroscopic
y Macule: flat, circumscribed, discoloration
y Papule: elevated solid area
e
5 mm.y Nodule: elevated solid area > 5 mm.
y Plaque: elevated flat-topped > 5mm.
y Vesicle: elevated fluid-filled e 5 mm.
y Bulla: elevated fluid-filled > 5 mm.
y Blister: common term for vesicle or bulla
y Pustule: discrete, pus-filled raised area
y Wheal: pruritic, erythematous elevated area
resulting from dermal edema.
y Scale: dry, plate-like excrescence resulting from
aberrant cornification.
y Lichenification: thick, rough skin with prominent
skin markings, usually due to repeated rubbing.
y Excoriation: linear, traumatic lesion resulting in
epidermal breakage.
y Onycholysis: loss of nail substance.
Microscopic
y Hyperkeratosis: stratum corneum hyperplasia, with
aberrant keratinization.
y Parakeratosis: retention of nuclei in stratum
corneum, normal in mucous membranes.
y Acanthosis: epidermal hyperplasia
y Dyskeratosis: abnormal keratinization below the
stratum granulosum.
y Papillomatosis: elongation or widening of thedermal papillae.
y Lentiginous: linear pattern of melanocyte
proliferation within the epidermal basal cell layer,
reactive or neoplastic.
y Spongiosis: epidermal intercellular edema.
y Exocytosis: inflammatory cells infiltrating the
epidermis.
y Erosion: focal, incomplete loss of epidermis.
y Ulceration: focal, complete loss of epidermis; may
include dermis and subcutaneous fat.
y Vacuolization: vacuoles within or adjacent to cells.
ACUTE INFLAMMATORY DERMATOSES short-lived, mononuclear cell infiltrates with
edema, local tissue damage
URTICARIA (HIVES)
ACUTE ECZEMATOUS DERMATITIS
ERYTHEMA MULTIFORME
ERYTHEMA NODOSUM and ERYTHEMA
INDURATUM
URTICARIA (HIVES)
focal mast cell degranulation
o histamine release: pruritus
edema
wheal
Angioedema:
o dermal
o SC fat edema
Perivascular mononuclear infiltrates and edema
Mediated by Ag-specific IgE or IgE-independent
(chemical-induced, PGs suppression)
Persistent inability to clear the inciting Ag,
cryptic collagen-vascular disorders, Hodgkin/s
disease
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HEREDITARY ANGIONEUROTIC EDEMA
Recurrent attacks
With GIT and laryngeal involvement
Deficient C1 esterase inhibitor
Unregulated activation of the early complement
components
ACUTE ECZEMATOUS DERMATITIS
Pathogenetically different w/ same histologicfeatures
Cutaneous delayed-type HS response
Cytokine release and nonspecific recruitment of
inflammatory cells
Gross:
: pruritic
: red
: papulovesicular to blistered
: oozing and subsequently crusted
: may evolve into psoriasis-like scaling plaques
Micro:
: spongiosis, progressive fluid accumulation,
intraepidermal vesicles;
: dermal perivascular lymphocytic infiltrate, mast
cell degranulation, papillary dermal edema;
: eosinophils (drug);
: progressive acanthosis & hyperkeratosis
(chronic)
5 PRIMARY TYPES OF ECZEMA
A. Contact DermatitisB. Atopic Dermatitis
C. Drug-Related Eczematous Dermatitis
D. Photo-Eczematous Eruption
E. Primary Irritant Dermatitis
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ERYTHEMA MULTIFORME
Uncommon, self-limited
HS response
o Drugs
o Infections
o systemic disorders
Extensive epidermal degeneration and necrosis
Due to cell-mediated immune injury
(CD8+ cytotoxic T-cells)
Gross
: multiform
o Macules
o Papules
o Vesicles &
o Bullae
: targets
o red maculopapular with central
vesicular or eroded pallor
: symmetric involvement of extremities
Steven-Johnson syndrome:
severe, febrile, erosions and hemorrhagic
crustingToxic Epidermal
Necrolysis:
diffuse mucocutaneous epithelial necrosis and
sloughing;
analogous to 3° burns
Micro
: dermoepidermal junction & superficial
perivascular lymphocytic infiltrates;
: dermal edema, focal basal keratinocyte
degeneration and necrosis;
: Exocytosis with epidermal necrosis, blistering
and shallow erosions;
: Target lesions central epidermal necrosis w/
perivenular inflammation
ERYTHEMA NODOSUM/INDURATUM
Panniculitis or inflammation of SC fat
o Connective tissue septa NODOSUM
o Fat lobules INDURATUM
may be Acute or Chronic
Early lesions: necrotizing vasculitis in deep
dermis and subcutis
Eventually develop granulomatous
inflammation and necrosis
Erythema Nodosum
Most common, acute onset
Idiopathic or Secondary
o Drugs
o Infections
o Sarcoidosis
o IBD
o visceral malignancy
Ill-defined, tender erythematous nodules with
fever and malaise
Old lesions flatten, ecchymotic without scarring
while new lesions develop Bx:
o early septal widening edema
o fibrin deposition
o neutrophil infiltration (giant cells &
eosinophils) w/o vasculitis
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Erythema Induratum
Uncommon, unknown cause
Adolescent and menopausal women
Primary vasculitis of SC fat with subsequent
inflammation and necrosis of adipose tissue
Erythematous, slightly tender nodule that
ulcerates and scars
Early: necrotizing vasculitis in deep dermis and subcutisLate: fat lobules develop granulomatous inflammation
and necrosis
Weber-Christian disease (Relapsing Febrile Nodular
Panniculitis)
Rare form of panniculitis; crops of
erythematous plaques or nodules, mainly on
the legs
Deep lymphohistiocytic infiltrates and giant
cells
Factitial Panniculitis
Self-administered foreign substances
Deep mycotic infections in
immunocompromised Others: SLE
CHRONIC INFLAMMATORY DERMATOSES
Persistent inflammatory disorders
Scaling and shedding (desquamation)
PSORIASIS
LICHEN PLANUSLUPUS
ERYTHEMATOSUS
ACNE VULGARIS
PSORIASIS
Common, HLA types (genetic)
New lesions at sites of trauma (Koebners
phenomenon) exogenous stimuli
Damage to stratum corneum - deposition of
complement- fixing Abs with 20
complement-mediated injury
Psoriatic endothelium sensitive to
cytokine-induced expression of adhesion
molecules with subsequent enhanced
neutrophil recruitment
Associated with other disorders:
o myopathies
o enteropathies
o AIDS
o arthritis
Gross:
: well-demarcated salmon pink plaques with
silvery scaling;
: elbows, knees, scalp, lumbosacral area,
intergluteal cleft, glans penis
Annular, linear, gyrate or serpiginous
ERYTHRODERMA - total body scaling and erythema
Nail changes: discoloration, pitting, onycholysis
Pustular psoriasis: rare, life-threatening
Micro:
: marked acanthosis with rete elongation,
mitoses above the basal layer;
: thin or absent stratum granulosum;
: extensive overlying parakeratosis
Thin epidermis overlying dermal papillae with dilated
vessels pinpoint bleeds when overlying scale isremoved (Auspitz sign)
Aggregates of neutrophils in epidermis within small
spongiotic foci in the stratum spinosum (spongiform
pustules) or within the parakeratotic stratum corneum
(Munros microabscesses); large, abscess-like
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LICHEN PLANUS
Unknown cause, self-limited, after 1 to 2 yrs
Leaves postinflammatory hyperpigmentation
Oral may persist, may become malignant
Cell-mediated immune injury to basal cells
With Koebners phenomenon
Gross
: pruritic, purple, polygonal papules that may
coalesce into plaques;
: highlighted by white dots or lines
(Wickhams striae)
Multiple, symmetrically distributed; hair follicle
epithelium (lichen planopilaris)
Micro:
: dense, bank-like dermoepidermal junction
lymphocytic infiltrate with basal cell
degeneration and necrosis;
: jagged rete saw- toothingNecrotic basal cells
may be sloughed into inflamed papillary dermis
forming colloid or Civatte bodies
With chronic changes: acanthosis, hyperkeratosis, thickgranular cell layer
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LUPUS ERYTHEMATOSUS
Discoid LE localized cutaneous form w/o
systemic manifestation
Immune complex-mediated and cell-mediated
injury to pigment-containing basal cells
Sun exposure exacerbates the lesion
Gross
: ill-defined malar erythema;: sharply demarcated discoid erythematous
scaling plaques with zones of irregular
pigmentation
: small keratotic plugs in hair follicles
Micro
: dermoepidermal junction perivascular &
: periappendiceal lymphocytic infiltrates
Preferential involvement of SC fat lupus profundus
Basal cell vacuolization, epidermal atrophy, variable
hyperkeratosis
Immunofluorescence:
: granular band along the dermoepidermal
and dermal-follicular junctions (lupus band
test)
ACNE VULGARIS
Common, chronic, inflammatory dermatosis
affecting hair follicles
Middle to late teens, males>females
Hormonal changes, alteration in hair follicle
maturations, infection (P. acnes)
Sex hormones, corticosteroid, occupational
exposure, occlusive conditions, heritable
component Lipase degradation of sebaceous oils to
highly irritating fatty acids
Antibiotics and vit. A (retinoic acid)
Gross
: Non-inflammatory follicular papules with
central black keratin plugs (open comedo);
: follicular papules w/ central plugs trapped
beneath the epidermis (closed comedo)
Rupture Inflammatory: erythematous papules,
nodules, pustules
Micro
: lipid & keratin at the midportion of hair follicles,
follicular dilatation;
: epithelial and sebaceous gland atrophy
Lymphohistiocytic infiltrates; acute & chronic
inflammation with scar formation
BLISTERING (BULLOUS) DERMATITIS
Primary conditions; level of blister involvementwithin the skin
o SUBCORNEAL: impetigo, p. follaceus
o SUPRABASAL: p. vulgaris
o SUBEPIDERMAL: bullous pemphigoid,
dermatitis herpetiformis
PEMPHIGUS
BULLOUS PEMPHIGOID
DERMATITIS HERPETIFORMIS
PEMPHIGUS
Rare, autoimmune, 4th
to 6th
decades Circulating Abs to keratinocyte intercellular
cement components that bind and trigger
release of plasminogen activator by
keratinocytes
FOUR variants:
1. P. vulgaris
2. P. vegetans
3. P. foliaceus
4. P. erythematosus
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Pemphigus vulgaris
80%; oral mucosa, scalp, face, intertriginous
zones, trunk, pressure points
Superficial and easily ruptures that leave
shallow & crusted erosions
Untreated uniformly fatal
Pemphigus vegetans
Rare; large, moist verrucous plaques studdedwith pustules
Flexural and intertriginous zones
Pemphigus foliaceus
More benign, epidemic in S. America
Face, scalp and upper trunk
Extremely superficial bullae leaving only slight
erythema and crusting after rupture
Pemphigus erythematosus
Localized, milder variant of P. foliaceus
Malar zone on the face
Micro
: acantholysis leading to intercellular clefting and
broad-based intraepidermal blisters
P. vulgaris & vegetans: immediately above the basal
layer (suprabasal blisters)
P. foliaceus: stratum granulosum
Immunofluorescence staining around each keratinocyte
(anti-Ig and anti-complement)
BULLOUS PEMPHIGOID
Common, autoimmune, elderly
Circulating Abs, with complement activation
and granulocyte recruitment, against Ags of the
lamina lucida in the epidermal BM
underlying lymphoreticular neoplasm
Gross
: tense bullae (up to 8 cm) w/ clear fluid, do not
rupture easily and heal w/o scarring
Micro
: subepidermal nonacantholytic blister;
: linear dermoepidermal junction fluorescence;
: superficial perivascular infiltrates
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DERMATITIS HERPETIFORMIS
Rare, 3rd to 4th decade, m>f
specific HLA types & celiac disease
Skin & GI lesions respond to gluten-free diet
Immune complex deposition in the skin
Anti-gliadin Abs cross reacting with junction
anchoring components (reticulin)
Granular IgA deposits dermal papillae tips
Gross
: Pruritic
: urticarial plaques & vesicles
: symmetric (extensors, upper back & buttock)
Micro
: neutrophils & fibrin accumulate in the tips of
dermal papillae (microabscesses) with overlying
basal vacuolization;
: microscopic blisters coalescing to large
subepidermal blisters
NONINFLA
MMA
TORYBL
ISTERING
DISEA
SES
Primary disorders with vesicles and bullae NOT
mediated by inflammatory mechanisms
PORPHYRIAE
PIDERMOLYSIS BULLOSA
PORPHYRIA
Inborn or acquired disturbances of porphyrin
metabolismUnknown pathogenesis
Urticaria and vesicles exacerbated by sun
exposure; heals w/o scarring
Subepidermal vesicles with marked superficial
dermal vascular thickening
EPIDERMOLYSIS BULLOSA Blistering at pressure sites and trauma
TYPES:
o JUNCTIONAL:
blistering at the lamina lucida
o DYSTROPHIC:
scarring, blistering beneath the
lamina lucida due to defective
anchoring fibrils
o SIMPLEX:
epidermal basal cell
degeneration
INFECTION and INFESTATION
VERRUCAE (WARTS)
MOLLUSCUM CONTAGIOSUM
IMPETIGO
LEPROSY
SUPERFICIAL FUNGAL INFECTIONS
ARTHROPOD-ASSOCIATED LESIONS
VERRUCAE (WARTS)
Common, HPV, direct contact
V. Vulgaris:o most common, dorsum of hand
o gray-white to tan
o flat to convex
o up to 1 cm. papules with rough pebbly
surface
V. plana (flat wart):
o face or dorsum of hand
o flat, smooth, small, tan papules
V. plantaris or palmaris:
o rough, scaly, up to 2 cm
o may coalesce - confused wit
hcallous Condyloma acuminatum (Anogenital and
Venereal Warts):
o soft, tan, cauliflower-like
Micro
: undulant (verrucous) epidermal hyperplasia and
koilocytosis
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MOLLUSCUM CONTAGIOSUM
Common, poxvirus, direct contact
Gross
: firm, pruritic
: pink to skin-colored
: umbilicated papules, up to 2 cm
: trunk & anogenital regions
Cheezy material with molluscum bodies expressed from
central umbilication
Micro: cuplike verrucous epidermal hyperplasia with
molluscum bodies (large eosinophilic cytoplasmic
inclusions in the stratum granulosum or corneum)
IMPETIGO
Streptococcal & Staphylococcal infection
erythematous macule progressing to smallpapules and eventually shallow erosion with
honey-colored crust
Micro
: subcorneal pustules filled with neutrophils and
Gm+ cocci
: dermal inflammation
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Pustule rupture releases serum and necrotic debris to
form the crust
LEPROSY
slowly progressive, unsightly & disabling
deformities, peripheral neural sensory deficits
Aerosol transmission, bipolar disease
o TUBERCULOID
Granulomas
(+) 48-hr lepromin test
o LEPROMATOUS anergic to lepromin
nodular lesions with
macrophages stuffed with
bacilli
may coalesce leonine facie
SUPERFICIAL FUNGAL INFECTIONS
Dermatophytes; confined to nonviable stratum
corneum; by location
Reactive epidermal changes similar to mild
eczematous dermatitis
Tinea capitis
asymptomatic hairless patches
mild erythema, crusting and scales
Tinea barbae
beard area among adult men
Tinea corporis excessive heat & humidity
infected animals, chronic infection of
the feet/nails;
expanding erythematous plaque with
elevated scaling border ringworm
Tinea cruris
inguinal areas among obese, warm
weather;
moist patches with raised scaling
borders
Tinea pedis (A
th
letes foot)
erythema & scaling in the webbed
spaces
2O bacterial infections
Onychomycosis:
Discoloration
thickening and deformity of the nail
plate
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Tinea versicolor:
Malassezia furfur
upper trunk
vari- sized hyper- or hypopigmented
macules with peripheral scale
ARTHROPOD-ASSOCIATED LESIONS
Bites, stings, infestations
Reactions: trivial to fatal
Gross
urticarial, inflamed papules or nodules
expanding erythematous plaques (erythema
migrans)
Direct irritant effect
Immediate IgE-mediated or delayed cell-
mediated HS Rxn
Specific effects of venom
Associated with secondary invaders
SCABIES
Pruritic caused by mite Sarcoptes scabiei
Female burrows beneath the stratum corneum
linear, poorly defined furrows:
o interdigital skin
o palms
o wrists
o periareolar area
o scrotal folds
PEDICULOSIS Pruritic, caused by louse: insect or eggs attach
to hair shafts
May be complicated by impetigo with
lymphadenopathy; urticaria-like
Excoriations and hyperpigmentation
Micro
: wedge-shaped dermal perivascular
lymphohistiocytic and eosinophilic infiltrates;
: central zone of epidermal necrosis w/
birefringent insect mouth parts;: florid inflammatory infiltrates or spongiosis
intraepidermal blisters
DISORDERS OF PIGMENTATION AND MELANOCYTES
VITILIGO
FRECKLE (EPHELIS)
MELASMA
LENTIGO
NEVOCELLULAR NEVUS (PIGMENTED NEVUS,
MOLE)
DYSPLASTIC NEVI
MELANOMA
VITILIGO
Irregular, well-demarcated macules devoid of
pigmentation
Autoimmunity (melanocyte autoAbs, T-cell
abnormalities);neurohormonal factors;
toxic intermediates in melanin synthesis
Micro: loss of melanocytes
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FRECKLE (EPHELIS)
Pigmented lesions:
o tan-red to brown macules occurring
after sun exposure
o fading and recurring with subsequent
cycles of winter and summer
Micro
: normal melanocyte number: ?slight hypertrophy
: increased melanin within basal keratinocytes
MELASMA
Masklike facial hyperpigmentation
Hyperestrogenic states, fades postpartum
Gross
: blotchy, irregular, ill-defined macules;
: accentuated by sunlight
Enhanced melanin transfer from melanocytes to other
cell types w/ subsequent accumulation
Micro
: increased melanin deposition in basal layers
(epidermal type);
: papillary dermal macrophage phagocytosis of
melanin released from the epidermis pigment
incontinence (dermal type)
LENTIGO
Benign, hyperpigmented macules, do notdarken with sun exposure
Unknown etiology and pathogenesis
Micro
: linear basal hyperpigmentation due to
melanocyte hyperplasia;
: with elongation and thinning of rete ridges
NEVOCELLULAR NEVUS
Group of congenital or acquired melanocyte
neoplasm Well-demarcated, tan-brown papules
Melanocytes derive from basal dendritic cells
that differentiate into round-to-oval cells with
uniform nuclei and prominent nucleoli
Natural History:
Begin as well-defined nests along the
dermoepidermal junction (junctional nevi);
lentigo-like (lentiginous) melanocyte
proliferation Extension of melanocytes forms
nests within both dermis and epidermis
(compound nevi)
Lost epidermal component resulting in dermal
nevi
Progressive dermal downgrowth, nevus cells
undergo maturation to resemble neural tissue
Variants: Congenital nevus
Blue nevus
Spindle & Epithelioid cell (Spitz) nevus
Halo nevus
Dysplastic nevus
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DYSPLASTIC NEVUS
Autosomal dominant or sporadic
Larger than acquired nevi; as hundreds of
irregular macules/plaques with pigment
variegation in both sun-exposed and
nonexposed skin
Micro
: cytologic and architectural atypia;
: enlarged & fused epidermal nevus cell nests,
: lentiginous hyperplasia,
: linear dermo- epidermal junction fibrosis,
: pigment incontinence
MELANOMA
Sun exposure, lightly pigmented individuals,
hereditary component
Pruritic, variegated, irregular maculopapular
lesions; CHANGE IN COLORATION
Initially extends horizontally within the
epidermis and superficial dermis (RADIAL
GROWTH PHASE);
dont metastasize LENTIGO MALIGNA and
SUPERFICIAL SPREADING
V
ERTICAL
G
ROW
TH
PHA
SE extension into th
edeep dermis, loss of cellular maturation, devt
of the capacity to metastasize
Clinical behavior & probability of metastasis:
: characteristics and depth of invasion of the
vertical growth; mitotic rates and degree of
lymphocytic infiltrates
Micro
: melanoma cells larger than nevus cells,
irregular nuclei, prominent eosinophilic
nucleoli;
: grow as loose nests lacking melanocyte
maturation
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BENIGN EPITHELIAL TUMORS
biologically inconsequential lesions derived
from keratinocytes or skin appendages
SEBORRHEIC KERATOSIS
ACANTHOSIS NIGRICANS
FIBROEPITHELIAL POLYP
EPITHELIAL CYST (WEN)
KERATOACANTHOMA
ADNEXAL (APPENDAGE) TUMORS
SEBORRHEIC KERATOSIS
Spontaneous lesions; trunk, smaller facial
lesions (dermatosis papulosa nigra)
Large number as part of paraneoplastic
syndrome (sign of Leser-Trelat) due to tumor
elaboration of growth factors]
Gross
: Uniform
: tan-brown
: velvety/granular, round plaques
: keratin-filled plugs
Micro
: exophytic, hyperplasia of basaloid cells
: hyperkeratosis
: keratin-filled horn cysts
ACANTHOSIS NIGRICANS
Thick hyperpigmented zones in flexural areas
Associated with benign or malignant conditions
elsewhere in the body
BENIGN
: 80%
: childhood through puberty
: autosomal dominant: obesity or endocrine disorders
: part of rare congenital disorders
MALIGNANT
: middle-aged & older
: occult adenocarcinoma
Micro
: Hyperkeratosis
: prominent rete ridges
: basal hyperpigmentation w/o melanocyte
hyperplasia
FIRBOEPITHELIAL POLYP
Acrochordon, squamous papilloma, skin tag
Soft, flesh-colored attached by slender stalk
with fibrovascular core covered by benign
epidermis
Associated with pregnancy, diabetes or
intestinal polyposis
EPITHELIAL CYSTS
Well-circumscribed, firm,SC nodules
Downgrowth and cystic
expansion of the epidermal
and follicular epithelium
Micro - based on cyst wall characteristic
: Epidermal Inclusion Cyst
o normal epidermis
: Pilar (Trichilemmal) Cyst
o follicular epithelium w/o granular cell
layer: Dermoid Cyst
o epidermis w/ multiple skin appendages,
hair follicles
: Steatocystoma multiplex
o sebaceous gland
ductal epithelium
w/ numerous
compressed
sebaceous lobules
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KERATOACANTHOMA
Spontaneously heal, rapidly growing, sun-exposed
Gross
: flesh-colored, superficial
: with central keratin-filled craters
: face/hands
Micro
: cup-shaped epithelial proliferations w/ atypical
cells, enclose central keratin-filled plug
Pattern of keratinization recapitulates hair follicle (no
granular cell layer)
Minimal inflammation during rapid proliferative phase;
evolves dermal inflammation and fibrosis; eventually
regress & disappear
ADNEXAL (APPENDAGE) TUMORS
Benign neoplasms, few malignant variants;
Mendelian pattern; indicate visceral malignancy
(Cowdens syndrome multiple
trichilemmomas with breast Ca)
Single or multiple, nondescript papules and
nodules, site predilection
Ex:
Cylindromas
Syringomas
Trichoepitheliomas
Trichilemmomas
SebaceousGland Adenoma/Adenocarcinoma
PREMALIGNANT AND MALIGNANT EPIDERMATUMORS
ACTINIC KERATOSIS
BOWENS/BOWENOID LESIONS and
ERYTHROPLASIA OF Q UEYRAT
SQ UAMOUS CELL CARCINOMA
BASAL CELL CARCINOMA
MERKEL CELL CARCINOMA
ACTINIC KERATOSIS
Premalignant dysplastic lesion, chronic sun
exposure;
ionizing radiation, hydrocarbons, and arsenicals
Gross
: tan-brown, red or flesh-colored
: rough consistency, cutaneous horns
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Micro
: cytologic atypia in the lower epidermis, parabasal
cell hyperplasia, dyskeratosis
: hyperkeratosis, parakeratosis;
: epidermal atrophy;
: dermis is thick with blue-gray elastic fibers
(elastosis)
CARCINOMA IN-SITU
Full thickness epidermal cytologic atypia (Bowens
disease; Bowenoid papulosis; Erythroplasia of
Queyrat)
Perineal/groin area with erythematous patches;
leukoplakia; well-demarcated, red, scaling plaques
Micro
: entire thickness of epidermis exhibits cytologic
nuclear atypia
SQ UAMOUS CELL CARCINOMA
Most common; sunlight/UV light directly damag
DNA & exerts immuno-suppressive effect to
Langerhans cells; industrial carcinogens, chroniskin ulcers, old burn scars, draining osteomyeliti
ionizing radiation, tobacco or betel nut chewing
Immunosuppression; xeroderma pigmentosum;
HPV infection
Gross
: nodular, variably hyperkeratotic, ulcerates;
: leukoplakia (mucosal surface)
:
May metastasize to regional LN
Micro
: from well differentiated to highly anaplastic wit
necrosis & abortion keratinization
BASAL CELL CARCINOMA
Common, slow-growing, sun-exposed and rarely
metastasize
Immunosuppression & xeroderma pigmentosum
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Gross
: pearly papules or expanding plaques;
: may be pigmented;
: ulcerate with extensive local invasion rodent
ulcer
Micro
: basal cell proliferation extending deeply into the
dermis; superficial or nodular
MERKEL CELL CARCINOMA
Rare, neural crest derived Merkel cells (tactile
sensation)
Potentially lethal
small, round malignant cells containing
neurosecretory type cytoplasmic granules
Resemble small cell Ca of the lung
TUMORS OF THE DERMIS
BENIGN FIBROUS HISTIOCYTOMA
DERMATOFIBROSARCOMA PROTUBERANS
XANTHOMAS
DERMAL VASCULAR TUMORS
BENIGN FIBROUS HISTIOCYTOMA
Indolent neoplasms of dermal fibroblasts & histiocyt
Unknown cause, antecedent trauma and aberrant
healing
Gross
: tan-brown, firm papules, may be tender;
: lateral compression exert dimpling
Micro
: dermatofibroma spindle shaped fibroblasts,
unencapsulated in the mid-dermis extending to SC f
DERMATOFIBROSARCOMA PROTUBERANS
Well-differentiated, slow-growing fibrosarcoma;
locally aggressive but rarely metastasize
Gross
: firm solid nodules arising as protuberant, ulcerated
aggregates within an indurated plaque
: Micro
: radially oriented (storiform) fibroblasts;
: scanty mitosis;
: thin overlying epidermis with extension into SC f
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XANTHOMAS
Not true neoplasm, focal accumulation of foamy
histiocytes
Idiopathic or Secondary (familial or acquired
hyperlipidemias, lymphoproliferative disorders)
Types (gross & hyperlipidemia):
Eruptive Xanthomao sudden showers of yellow papules that
wax & wane w/ plasma triglycerides & lipid
levels
Tuberous Xanthoma
o yellow, flat-to-round nodules over the
joints
Tendinous Xanthoma
o yellow nodules over the Achilles tendon
and finger extensor tendons
Plane Xanthoma
o linear yellow lesions in skin folds (palmarcreases); 1O biliary cirrhosis
Xanthelasma
o soft yellow plaques on the eyelids
Micro
: dermal aggregates of macrophages with
vacuolated cytoplasm containing cholesterol,
phospholipids, and triglycerides
DERMAL VASCULAR TUMORS
Hemangiomas
vascular malignant tumors
Kaposis sarcoma and
angiomatosis
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TUMORS OF CELLULAR IMMIGRANTS TO THESKIN
Proliferative disorders of cells arising elsewhere
but which homed to the skin
HISTIOCYTOSIS X
MYCOSIS FUNGOIDES (CUTANEOUS T-CELL
LYMPHOMA)
MASTOCYTOSIS
HISTIOCYTOSIS X
Cutaneous form solitary or multiple papules or
nodules;
scaling erythematous plaques resembling
seborrheic dermatitis
Histo
: variable numbers of eosinophils and different
patterns:
o Diffuse dermal infiltrates of mononuclear
cells with
bland, indented nucleio Similar cells clustered to resemble
granulomas
o Dermal infiltrates composed of
mononuclear cells with foamy cytoplasm
Birbeck granules, CD1 Ags Langerhans cell derivation
MYCOSIS FUNGOIDES
Cutaneous T-cell Lymphoma, 3 patterns
o Mycosis Fungoides (MF)
o MF demblee: nodular eruptive variant
o Adult T-cell leukemia or lymphoma: aggressive
course,HTLV-1
Lymphoproliferative disorder arising from the skin &
eventually seed the blood (Sezarys syndrome) and
evolve into more generalized T- cell leukemia or
lymphoma
Gross
: eczema-like lesions evolving into scaly, red- brown
patches or plaques; to nodules (nodular cutaneous
growth deep dermal invasion;
: onset of LN & visceral involvement)
Micro
: Sezary-Lutzner cell malignant CD4-positive (T-
helper) cell with hyperconvoluted or cerebrifor
nucleus;
: band-like dermal infiltrates with invasion of sing
cells or small clusters into the epidermis (Pautrie
microabscess)
MASTOCYTOSIS
Rare, cutaneous (visceral) mast cell proliferation
degranulation (histamine and heparin)
Pruritus & flushing specific foods, temperature
alcohol, certain drugs
Dermal edema & erythema (wheal) when skin
(Dariers sign) or normal skin (dermatographism
rubbed
Epistaxis or GI bleeding
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Urticaria pigmentosa (50%) exclusively cutaneous,
favorable prognosis, children;
10% adults, systemic, poorer prognosis
Gross
: multiple, round-to-oval, nonscaling
: red- brown papules & plaques
Micro
: dermal fibrosis
: edema
: eosinophils and
: mast cells