Pathology of the Skin Flashcards by Vincent Ribaya

Macroscopic lesion:

Traumatic lesion breaking the epidermis and causing a raw linear area (i.e.: deep scratch); often self-induced

Excoriation

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Macroscopic lesion:

Thickened, rough skin (similar to lichen growth on a rock); usually the result of repetitive rubbing

Lichenification

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Macroscopic lesion:

Circumscribed flat lesion usually distinguished from surrounding skin by color, = 5 mm in diameter

Macule

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Macroscopic lesion:

Circumscribed flat lesion usually distinguished from surrounding skin by color, > 5 mm in diameter

Patch

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Macroscopic lesion:

Separation of nail plate from nail bed

Onycholysis

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Macroscopic lesion:

Elevated dome-shaped or flat-topped lesion = 5 mm diameter

Papule

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Macroscopic lesion:

Elevated dome-shaped lesion > 5 mm diameter

Nodule

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Macroscopic lesion:

Elevated flat-topped lesion > 5 mm diameter; may be formed by coalescence of papules

Plaque

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Macroscopic lesion:

Dry, horny, plate-like excrescence; usually the result of imperfect cornification

Scale

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Macroscopic lesion:

General term of a fluid-filled raised lesion

Blister

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Macroscopic lesion:

Fluid-filled raised lesion = 5 mm diameter

Vesicle

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Macroscopic lesion:

Fluid-filled raised lesion > 5 mm diameter

Bulla

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Macroscopic lesion:

Itchy, transient, elevated lesion with variable blanching and erythema formed as the result of dermal edema

Wheal

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Microscopic lesion:

Diffuse epidermal hyperplasia

Acanthosis

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Microscopic lesion:

Loss of intercellular connections between keratinocytes

Acantholysis

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Microscopic lesion:

Abnormal, premature keratinization within cells below the stratum granulosum

Dyskeratosis

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Microscopic lesion:

Focal discontinuity of the skin showing incomplete loss of the epidermis

Erosion

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Microscopic lesion:

Infiltration of the epidermis by inflammatory cells

Exocytosis

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Microscopic lesion:

Intracellular edema of kertinocytes, often seen in viral infections

Hydropic swelling/ballooning

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Microscopic lesion:

Hyperplasia of the stratum granulosum, often due to intense rubbing

Hypergranulosis

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Microscopic lesion:

Hyperplasia of the stratum corneum, often associated with a qualitative abnormality of keratin

Hyperkeratosis

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Microscopic lesion:

A linear pattern of melanocyte proliferation within the basal cell layer

Lentiginous

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Microscopic lesion:

Surface elevation caused by hyperplasia and enlargement of contiguous dermal papillae

Papillomatosis

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Microscopic lesion:

Keratinization with retained nuclei in the stratum corneum (normal in mucous membranes)

Parakeratosis

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Microscopic lesion: Focal discontinuity of the skin showing complete loss of the epidermis, revealing dermis or subcutis

Ulceration

Microscopic lesion: Intercellular edema of the epidermis

Spongiosis

Microscopic lesion: Formation of vacuoles within or adjacent to cells; often refers to basal cell-basement membrane zone area

Vacuolization

Common nevus with the following description: - < 6 mm in diameter - uniformly pigmented - regular, well-defined - mostly in sun-exposed areas - no atypia, absent mitosis - no dermal reactions - RAS mutations (pro-growth signalling but intact tumor suppressant p16 prevents progression) - follows a maturation sequence

Melanocytic nevus

Common nevus with the following description: - > 5 mm in diameter - variegated pigments with pebbly surface - irregular borders, can be target-like with darker raised center and irregular flat periphery - found in both sun-exposed and non-sun-exposed areas - with lentiginous hyperplasia as nevus cells replace the normal basal cell layer along the dermo-epidermal junction - with atypia and mitosis - lymphocytic infiltration, linear fibrosis, and melanin incontinence - CDKN2A mutation (impaired tumor suppression activity), TERT (telomerase activation, prolonging cell life), RAS mutation (pro-growth signalling) - marker for melanoma risk - follows a turmor progression sequence

Dysplastic nevus

Syndrome of multiple (hundreds) of dysplastic nevi that is also a risk factor for melanoma

Dysplastic nevus syndrome

1st stage of melanocytic nevus MATURATION SEQUENCE: - nevus cells at the dermo-epidermal junction - growth pattern: nests - cells round, uniform, with inconspicuous nucleoli and no mitosis - tyrosinase-positive - cholinesterase-negative

Junctional nevus

2nd stage of melanocytic nevus MATURATION SEQUENCE: - nevus cells at the dermo-epidermal junction AND dermis - growth pattern: nests - cells round, uniform, with inconspicuous nucleoli and no mitosis - tyrosinase-positive - cholinesterase-negative

Compound nevus

3rd stage of melanocytic nevus MATURATION SEQUENCE: - nevus cells at the dermis - growth pattern: nests - cells round, uniform, with inconspicuous nucleoli and no mitosis - tyrosinase-positive - cholinesterase-negative

Intradermal nevus

4th stage of melanocytic nevus MATURATION SEQUENCE: - nevus cells at the dermis - growth pattern: fascicles - fusiform cells, spindle-shaped but non-dysplastic - tyrosinase-negative - cholinesterase-positive

Intradermal nevus with neurotization

Rate-limiting enzyme responsible for melanin regulation

Tyrosinase | Tyrosinase from melanocytes cleaves tyrosine, precursor to melanin and other pigments

1st stage of dysplastic nevus TUMOR PROGRESSION SEQUENCE: - involves the basal layer of the epidermis (dermo-epidermal junction) - no atypia and mitosis

Lentiginous junctional nevus

2nd stage of dysplastic nevus TUMOR PROGRESSION SEQUENCE: - involves the dermis and epidermis (with atypical cells in epidermis) - with atypia and mitosis

Lentiginous compound nevus

3rd stage of dysplastic nevus TUMOR PROGRESSION SEQUENCE: - involves the epidermis and superficial dermis - with atypia and mitosis - radial growth only

Early melanoma

4th stage of dysplastic nevus TUMOR PROGRESSION SEQUENCE: - involves the epidermis, dermis, and other structures - with atypia and mitosis - both radial and vertical growth

Advanced melanoma

Specific type of early melanoma confined to the epidermis of sun-damaged skin

Lentigo maligna melanoma

Specific type of melanoma with solely vertical growth (no radial growth)

Nodular melanoma

Most common specific type of melanoma, known to spread over the lower extremities and back

Superficial spreading melanoma

Specific type of melanoma confined to the sole, palm, or the areas beneath the nail; common in blacks

Acral melanoma

A rare autosomal recessive genetic disorder of DNA repair in which the ability to repair damage caused by ultraviolet (UV) light (especially on the skin) is deficient; also a known risk factor for melanoma

Xeroderma pigmentosum (XP)

5 clinical pearls of suspected melanoma

- Asymmetry - Irregular borders - Variegated color - Increasing diameter - Evolution (Mnemonic: ABCDE)

Special diagnostic silver-based stain for melanoma, nevus cells

Melanin stains

More specific immunostains used in the diagnosis of melanoma

S-100 and HMB-45

Prognostic scale of melanoma based on the measurement of tumor depth

Breslow thickness (or Breslow's depth)

Benign epithelial tumor with the following characteristics: - hyperpigmented, coin-like, macular-to-raised, verrucoid lesions with stuck-on appearance - basaloid cells with variable pigment production - hyperkeratosis - horn cysts (keratin-filled cysts) - invagination cysts (invaginations of keratin)

Seborrheic keratosis

Seborrheic keratoses presenting as multiple small facial lesions, commonly found in blacks

Dermatosis papulosa nigra

Rapid increase in the number of seborrheic keratoses as a paraneoplastic syndrome of gastric adenocarcinoma and other GI cancers

Leser-Trelat sign

Benign epithelial tumor with the following characteristics: - thickened, hyperpigmented skin with a velvet-like texture in flexural areas - cutaneous marker for benign conditions (DM, obesity) and some malignant conditions (GI cancers) - undulation of epidermis and dermal papillae - hyperkeratosis - basal cell hyperpigmentation without melanocytic hyperplasia

Acanthosis nigricans

Premalignant epidermal tumor with the following characteristics: - found on sun-damaged skin - tan-brown, red, or skin-colored - rough, sandpaper-like - may have cutaneous horns (overproduction of keratin) cytologic atypia in basal epidermis with intercellular bridging - atypical basal cells with pink/reddish cytoplasm (dyskeratosis) - blue-gray basophilic degenerative changes in the elastic fibers (solar elastosis) - stratum corneum cells retain their nuclei (parakeratosis) with hyperkeratosis = "hyperparakeratosis"

Actinic keratosis

Malignant epidermal tumor with the following characteristics: - second most common tumor arising in sun-exposed sites in older people - grossly as plaques, to nodules, to ulcers - mildly aggressive - commonly metastasizes - atypical SQUAMOUS cells involving full thickness of the epidermis with dermal invasion - keratin pearl formation - dyskeratosis

Squamous cell carcinoma (SCCA)

Malignant epidermal tumor with the following characteristics: - most common invasive cancers in humans - grossly as pearly papules with telangiectasia, and ulceration - very aggressive - rarely metastasizes - nests of BASALOID cells (looks like the cells from the basal layer) with peripheral palisading - stromal retraction

Basal cell carcinoma

Warty outgrowths caused by infection with human papillomavirus (HPV) 5 and 8, placing the patient in an immunosuppressed state, presenting as a major risk factor for SCCA

Epidermodysplasia verruciformis

Inherited medical condition involving defects within multiple body systems such as the skin, nervous system, eyes, endocrine system, and bones - includes multiple nevoid BCCA

Gorlin syndrome (or Gorlin-Goltz syndrome)

Characteristic large lesion of nodular BCCA that presents with central necrosis

Rodent ulcer (or Jacob's ulcer)

Inflammatory dermatosis with the following characteristics: - increased dermal microvascular permeability, presenting clinically as wheals - superficial dermal edema - sparse superficial perivenular mononuclear infiltrate - mast cell-mediated and IgE-mediated; type I hypersensitivity - mast cell-dependent; IgE-independent

Urticaria

Urticarial involvement of the deeper dermis and subcutaneous fat

Angioedema

Urticarial-like disorder that is BOTH mast cell and IgE-independent

Hereditary angioneurotic edema

Characteristic pruritic edematous plaque of urticaria

Wheal

Inflammatory dermatosis with the following characteristics: - red, papulovesicular, oozing, crusted lesions - raised, scaling plaques (reactive acanthosis and hyperkeratosis) - T cell-mediated; type IV hypersensitivity to contact antigens or internal circulating antigens (drugs) - CONTACT antigens cause SUPERFICIAL dermal perivascular MONONUCLEAR infiltrate - circulating/INTERNAL antigens cause both SUPERFICIAL and DEEP perivascular LYMPHOCYTIC infiltrate with EOSINOPHILS - hyperkeratosis, acanthosis, spongiosis - dermal edema may seep in to intracellular spaces of the stratum spinosum, causing intraepidermal vesicles

Acute eczematous dermatitis (or eczema) (Forms: - allergic contact dermatitis - atopic dermatitis - drug-related eczematous dermatitis - photoeczematous dermatitis - primary irritant dermatitis)

Inflammatory dermatosis with the following characteristics: - multiform and target lesions - interface dermatitis (lymphocytes at the dermo-epidermal junction associated with necrotic keratinocytes) - CD8+ T cell-mediated type IV hypersensitivity, associated with particular drugs, cancers, infections, and collagen vascular diseases - part of a spectrum encompassing SJS and TEN

Erythema multiforme (Associated drugs: - sulfonamides - penicillins - barbiturates - salicylates - antimalarials - hydantoins Associated infections: - HSV - Mycoplasma - histoplasmosis - Coccidiodes - salmonella - leprosy Associated cancers: - carcinomas - lymphomas Associated collagen vascular diseases: - SLE - polyarteritis nodosa (PAN) - dermatomyositis)

Erythema multiforme spectrum involving < 10% total BSA, including mucosal involvement and systemic symptoms

Steven-Johnson syndrome (SJS)

Erythema multiforme spectrum involving > 30% total BSA, with characteristic splitting of skin, formed by blisters occuring at the dermoepidermal junction

Toxic epidermal necrolysis (TEN) | Note: as opposed to staphylococcal SSS where splitting occurs at stratum granulosum due to bacterial toxin

Erythema multiforme spectrum involving 10-30% total BSA

SJS-TEN overlap

Inflammatory dermatosis with the following characteristics: - cell-mediated autoimmune dermatitis caused by CD4+ TH1, CD4+ TH17, and CD8+ accumulation in the epidermis - grossly with salmon-colored plaques covered by loosely adherent silvery-white scales usually seen on the sites of trauma - acanthosis with elongation of rete ridges (test tube rack appearance) - stratum granulosum thinned or absent with overlying parakeratotis (stratum corneum) scales - neutrophilic infiltrates in epidermis and within the parakeratotis stratum corneum

Psorias

Clinical sign where lifting of the silvery-white scales in psoriasis causes pinpoint bleeding due to the dilated tortuous vessels in the dermal papillae

Auspitz sign

Phenomenon in which psoriatic lesions tend to appear over areas of trauma - knees, elbows, scalp, lumbosacrum, intergluteal cleft, glans penis, etc.

Koebner phenomenon

Histologic finding in psoriasis of acanthosis with significantly elongated rete ridges

Test tube appearance

Inflammatory infiltrate in psoriasis, described as neutrophils in spongiotic foci of the superficial epidermis

Spongiform pustules of Kogoj

Inflammatory infiltrate in psoriasis, described as neutrophils within the parakeratotic stratum corneum

Munro micro-abscesses

Inflammatory dermatosis with the following characteristics: - high density of sebaceous glands - macules and papules on an erythematous-yellow, greasy base with extensive scaling and crusting - may be associated with Malassezia and/or immunosuppression - mounds of parakeratosis, with PMNs and serum at the ostia of hair follicles (FOLLICULAR LIPPING) - superficial perivascular inflammatory infiltrate (lymphocytes and neutrophils)

Seborrheic dermatitis

Seborrheic dermatitis of the scalp

Dandruff

Inflammatory dermatosis with the following characteristics: - pruritic, purple, polygonal, planar, papules and plaques (6 P's) - white dots/lines on papules (WICKHAM STRIAE) - may be T cell-mediated - epidermal hyperplasia (or rarely atrophy), hyperkeratosis, hypergranulosis - interface dermatitis - SAWTOOTHING of the DEJ - Anucleate, necrotic basal cells in inflammed papillary dermis (CIVATTE BODIES or COLLOID BODIES)

Lichen planus

Inflammatory blistering disease with the following characteristics: - targets desmoglein at the desmosomes - blisters located at the suprabasilar or subcorneal areas - involvement of mainly IgG antibodies - immunofluorescent at the intercellular squamous region (LACE-LIKE) - acantholysis - Nikolsksy sign-POSITIVE

Pemphigus

The more common type of pemphigus where blisters are located at the suprabasilar level; may involve mucosal surfaces

Pemphigus vulgaris

Less common type of pemphigus where blisters are located at the subcorneal level; endemic in Brazil; rarely involves mucosal surfaces

Pemphigus foliaceus

Pemphigus associated with non-Hodgkin lymphoma

Paraneoplastic pemphigus

Inflammatory blistering disease with the following characteristics: - antigens target hemidesmosomes - blisters located at subepidermal area - involvement of IgG antibodies - immunofluorescent at the epidermal basement membrane zone (LINEAR) - no acantholysis - basal cell layer vacuolization - Nikolsksy sign-NEGATIVE (tense bullae)

Bullous pemphigoid (or mucous membrane pemphigoid)

The dislodgement of intact superficial epidermis by a shearing force, indicating a plane of cleavage in the skin - used to differentiate pemphigus (positive) from a bullous phemphigoid (negative)

Nikolsky sign (dermo-epidermal separation)

Inflammatory blistering disease with the following characteristics: - antigens target reticulin (fibrils that anchor the epidermis to the superficial dermis) - blisters located at subepidermal area - involvement of IgA antibodies - immunofluorescent at the epidermal basement membrane zone (GRANULAR) - fibrin and PMNs at the tips of dermal papillae - associated with celiac disease

Dermatitis herpetiformis

Non-inflammatory blistering disease with the following characteristics: - defects in either keratin, laminin & BPAGs, or type VII collagen

Epidermolysis bullosa (EB)

Type of epidermolysis bullosa associated with defects in keratin (most common)

EB simplex

Type of epidermolysis bullosa associated with defects in laminin and bullous pemphigoid antigens (BPAGs)

Junctional EB

Type of epidermolysis bullosa associated with defects in type VII collagen (anchoring collagen)

Dystrophic EB

Non-inflammatory blistering disease with the following characteristics: - inherited defects in heme metabolism - accumulation of porphyrins in the skin - sun-induced skin damage

Porphyria

Disorder of epidermal appendage with the following characteristics: - chronic inflammation of the pilosebaceous unit - histological hallmark: comedones (comedogenesis) - keratin plug leads to sebaceous gland hypertrophy and the proliferation of Propionibacterium acne (lipase-synthesizing baction), leading to a secondary inflammation - universal in the middle-to-late teenage years - may be further precipitated by drugs (corticosteroids, ACTH, testosterone, gonadotropins, OCPs, trimethadione, iodides), occupational exposures (cutting oils, chlorinated hydrocarbons, coal tar), occlusive conditions (heavy clothing, cosmetics), and tropical climates

Acne vulgaris

Lesion of acne comedogenesis involving a small follicular papule with central black plug due to melanin oxidation

Open comedone (or the "blackhead")

Lesion of acne comedogenesis involving small follicular papule without any visible plug; keratin plug beneath epidermal surface

Closed comedone (or the "whitehead")

Skin infection caused by HPV: - gray-white to tan papules, flat-to-convex with pebbly surface - undulating papillomatous epidermal hyperplasia - koilocytic atypia (cytoplasmic vacuolization seen as a perinuclear halo)

Verruca

Skin infection caused by poxvirus: - pruritic, pink to skin-colored papules with central umbilication - large, ellipsoid, homogenous cytoplasmic inclusions in the stratum granulosum and stratum corneun (MOLLUSCUM BODIES)

Molluscum contagiosum

Skin infection caused by either Group A beta-hemolytic streptococci (Streptococus pyogenes) or Staphylococcus aureus: - honey-colored crusts - accumulation of neutrophils beneath the stratum corneum

Impetigo

Impetigo caused by Streptococcus pyogenes (GABHS)

Impetigo contagiosa

Impetigo caused by Staphylococcus aureus

Impetigo bullosa

Pathology of the Skin Flashcards

(96 cards)