CAQ-Derm flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

ABCDE melanoma criteria

Asymmetry, Border irregularity, Color variegation, Diameter >6 mm, and Evolution. Sensitivity is imperfect, so nodular and amelanotic melanomas may not satisfy these criteria.

Köbner phenomenon

Isomorphic skin lesions appearing at sites of trauma or injury. Classically seen in psoriasis, lichen planus, vitiligo, and molluscum contagiosum.

Nikolsky sign

Separation of the epidermis with lateral pressure. Positive in pemphigus vulgaris and toxic epidermal necrolysis; negative in bullous pemphigoid.

Auspitz sign

Pinpoint bleeding after removal of scale from a plaque. Reflects epidermal hyperproliferation and is classically described in psoriasis.

Darier sign

Wheal formation when a pigmented lesion is rubbed. Positive in urticaria pigmentosa and indicates mastocytosis with dermal mast cell infiltration.

Fitzpatrick sign

Dimpling of a firm nodule when compressed laterally. Characteristic of dermatofibroma, a benign fibrous histiocytoma.

Hutchinson sign

Pigment extending from the nail plate onto the cuticle. Raises concern for subungual melanoma and warrants biopsy.

Leser-Trélat sign

Sudden eruption of multiple seborrheic keratoses. Warrants evaluation for internal malignancy, especially gastrointestinal adenocarcinoma.

Pemphigus vulgaris

Flaccid intraepidermal bullae with mucosal involvement and positive Nikolsky sign. IgG against desmoglein 1 and 3 gives intercellular 'chicken wire' immunofluorescence.

Bullous pemphigoid

Tense subepidermal bullae in older adults with a negative Nikolsky sign. IgG against BP180 and BP230 gives linear basement membrane immunofluorescence.

Dermatitis herpetiformis

Intensely pruritic grouped vesicles on extensor surfaces with granular IgA at dermal papillae. Strongly associated with celiac disease; treated with dapsone and gluten-free diet.

Erythema multiforme

Target lesions with three zones, acrally distributed, usually triggered by herpes simplex virus. Mucosal involvement defines EM major.

Stevens-Johnson syndrome

Severe mucocutaneous drug reaction with epidermal detachment of less than 10% of body surface area. Requires drug withdrawal and burn-unit-level supportive care.

Toxic epidermal necrolysis

Severe mucocutaneous reaction with epidermal detachment greater than 30% of body surface area. High mortality; SCORTEN predicts in-hospital mortality.

DRESS syndrome

Drug reaction with eosinophilia and systemic symptoms: fever, morbilliform rash, facial edema, lymphadenopathy, eosinophilia, and organ involvement 2-8 weeks after drug exposure.

Erythema nodosum

Tender red nodules on the anterior shins with septal panniculitis. Associated with streptococcal infection, sarcoidosis, inflammatory bowel disease, and drugs.

Pityriasis rosea

Herald patch followed by oval scaly plaques in a Christmas tree distribution on the trunk. Self-limited over 6-8 weeks; linked to HHV-6/7 reactivation.

Lichen planus

Pruritic purple polygonal planar papules with Wickham striae. Mucosal involvement occurs; associated with hepatitis C; treated with topical corticosteroids.

Scabies

Intense nocturnal pruritus with burrows in web spaces and wrists. Treat with permethrin 5% or oral ivermectin and treat all close contacts simultaneously.

Herpes zoster

Dermatomal vesicular eruption with pain. Antivirals are most effective within 72 hours of rash onset; ophthalmic involvement requires urgent referral.

Tinea versicolor

Hypopigmented or hyperpigmented finely scaly macules on the trunk caused by Malassezia. KOH shows 'spaghetti and meatballs'; recurrence is common.

Basal cell carcinoma

Pearly papule with telangiectasia and a rolled border, often with central ulceration. Most common skin cancer; locally destructive but rarely metastasizes.

Squamous cell carcinoma

Hyperkeratotic or ulcerated nodule on sun-exposed skin arising from actinic keratosis. Higher metastatic risk than basal cell carcinoma, especially on lip and ear.

Actinic keratosis

Rough, sandpaper-like erythematous macules on sun-damaged skin. Treated with cryotherapy, topical 5-fluorouracil, imiquimod, or photodynamic therapy.

Breslow thickness

Depth of melanoma invasion in millimeters from the granular layer. Strongest predictor of survival; guides sentinel node biopsy and surgical margins.

Mohs micrographic surgery

Microscopically controlled excision with examination of 100% of the margin. Indicated for high-risk basal and squamous cell carcinoma; highest cure rate with tissue conservation.

Hidradenitis suppurativa

Recurrent painful nodules and abscesses in intertriginous areas. Associated with smoking and obesity; Hurley staging guides treatment, including antibiotics and adalimumab.

Isotretinoin monitoring

Teratogenic acne therapy requiring two negative pregnancy tests before initiation, monthly pregnancy tests, and two contraceptive methods. Monitor lipids and transaminases.

Methotrexate dosing

For psoriasis, methotrexate is dosed weekly, not daily. Supplement folic acid and monitor liver enzymes and blood counts; avoid in pregnancy.

Patch testing

Gold standard for allergic contact dermatitis. Standardized allergens applied and read at 48-72 and 96-120 hours to capture delayed reactions.

KOH preparation

Potassium hydroxide dissolves keratin to reveal hyphae, pseudohyphae, or budding yeast. Scrape scale from the active border of the lesion.

Wood's lamp

365 nm ultraviolet light used to detect fluorescence. Coral-red fluorescence suggests erythrasma; blue-green fluorescence suggests Microsporum tinea capitis.