24 - Skin Flashcards
Disease of depigmentation secondary to destruction of melanocytes.
Vitilligo
Disease of depigmentation secondary to decreased or absent synthesis of melanin.
Albinism
These are nevi, usually <6 mm, benign-looking, clinically and histologically, and are removed for cosmetic reasons; these lesions have RAS mutations but most never progress because of intact p16 (tumor-suppressor) activity.
Melanocytic nevus
These are large nevi (>5 mm) and may occur as hundreds of lesions on the body surface; they are flat macules to slightly raised plaques, with a “pebbly” surface; considered as a marker of melanoma risk.
Dysplastic nevi
The most deadly of all skin cancers; results from excessive sun exposure; malignant cells have large nuclei with irregular contours having chromatin characteristically clumped at the periphery of the nuclear membrane and prominent eosinophilic nucleoli often described as “cherry red”; has both radial and vertical growth phases.
Melanoma
Immunohistochemical staining for melanoma.
S-100, and HMB-45 (more specific)
- Clinically mimics melanoma; round, exophytic, coin-like plaques varying in diameter, with a velvety/granular surface; tan to dark brown in color; it has a stuck-on appearance often seen in older individuals; the lesions consist of an orderly proliferation of uniform, monotonous sheets of small cells (basaloid in appearance) with a tendency to form keratin microcysts
- another name for these keratin cysts:
- A paraneoplastic manifestation of GI malignancies that results to rapid increase in number of these lesions
- Seborrheic keratosis
- horn cysts
- Leser-Trelat sign
- Thickened, hyperpigmented skin with a velvet-like texture in flexural areas; important cutaneous marker of benign (obesity, DM) and malignant conditions (GI malignancies); basal cell hyperpigmentation without melanocytic hyperplasia
- acanthosis nigricans
This lesion is usually the result of chronic exposure to sunlight; dermis contains thickened, blue-gray elastic fibers or “solar elastosis” which is the result of chronic sun damage; grossly, lesions are less than 1cm, tan-brown or red in color, with sandpaper-like surface; microscopically, there is Atypical dyskeratotic cells in basal epidermis with intercellular bridges, solar elastosis, hyperparakeratosis and dermal chronic inflammation.
Actinic keratosis
- Second most common tumor arising on sun-exposed sites in older people, with higher incidence in women; may arise from prior actinic keratoses, then when advanced becomes nodular and may ulcerate; characterized by anaplastic (seen on all levels of the epidermis), rounded cells with foci of necrosis and only abortive, single-cell keratinization (dyskeratosis), with keratin pearl formation
- This condition results from hyperinfection with HPV, and is a risk factor for the tumor mentioned above:
- Squamous cell carcinoma
- epidermodysplacia verruciformis
- This is the most common invasive cancer in humans, which is a slow-growing tumor that rarely metastasizes; tends to occur at sites subject to chronic sun exposure and in lightly pigmented people; These tumors present as pearly, smooth-surfaced papules, often containing prominent, dilated subepidermal blood vessels (telangiectasia); the cells have scant cytoplasm, small hyperchromatic nuclei, and a peripheral palisade with clefting from the stroma.
- Term for the genetic syndrome that predisposes one to develop these lesions
- Basal cell carcinoma
- Gorlin syndrome
- Condition caused by local mast cell degranulation; histologically, there is usually a sparse superficial perivenular infiltrate of mononuclear cells with superficial dermal edema.
- two mechanisms by which this lesion arises:
- Urticaria
- mast-cell and IgE-dependent (Type I hypersensitivity)
- mast-cell and IgE-independent (Hereditary angioneurotic edema)
This term is the accumulation of edema fluid within the epidermis; characterizes all forms of eczamatous dermatitis.
Spongiosis
- An uncommon, usually self-limited disorder that seems to be a hypersensitivity response to certain infections and drugs; patients present with an array of “multiform” lesions, including macules, papules, vesicles, and bullae, as well as the characteristic targetoid lesion consisting of a red macule or papule with a pale vesicular or eroded center; part of a spectrum with SJS-TEN.
- Describe the SJS-TEN spectrum
- Erytherma multiforme
- SJS: < 10%
- SJS-TEN: 10-30%
- TEN: > 30%
- A skin disorder whose main pathology is increased epithelial cell turnover; there is acanthosis and loss of the stratum granulosum with extensive overlying parakeratotic scale; there is also a regular downward elongation of rete ridges (test tubes in a rack appearance); associated with multiple punctate hemorrhages upon removal of scales from the lesions (Auspitz sign) due to presence of dilated tortuous vessels.
- Small aggregates of neutrophils within the parakeratotic stratum corneum
- Neutrophils in spongiotic foci of superficial epidermis
- Psoriasis
- Munro microabscesses
- Pustules of Kogoj
“Pruritic, purple, polygonal, planar papules, and plaques” describes this disorder of the skin and mucosa. Also noted grossly are Wickham striae, which are white lacelike markings over the papules; pattern of inflammation of this disorder is characterized by angulated, zigzag contour (“sawtoothing”) of the dermoepidermal junction.
Lichen planus
A rare autoimmune blistering disorder resulting from loss of integrity of normal intercellular attachments within the epidermis and mucosal epithelium; caused by a Type II hypersensitivity reaction (mainly IgG) against desmoglein; histologically characterized by acantholysis immediately above the basal layer.
Pemphigus vulgaris
Also an autoimmune blistering disease against the epidermal basement membrane components (hemidesmosomes); however, it is characterized by subepidermal nonacantholytic blisters.
Bullous pemphigoid
Associated with celiac disease; clinically characterized by pruritic urticarial; histologically characterized by subepidermal blisters that develop from coalescence of vacuolized microabscesses at the dermal papilla tips.
Dermatitis herpetiformis
A skin infection caused by either S. aureus (characterized by formation of bullae) or S. pyogenes (characterized by appearance of honey-colored crusts); histologically characterized by subcorneal neutrophilic infiltration.
Impetigo
A benign lesion cause by low-risk strains of HPV (2, 4 and 7); characterized by koilocytic atypia (cytoplasmic vacuolization).
Verrucae
