11. Diseases of the Skin (2)

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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



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



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



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



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



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



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



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



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



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



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



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



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 dermoepidermal 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



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



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



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



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



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



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



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

Documents

11. Diseases of the Skin (2)