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
