Hair, Nail and Mucosal Disorders
Scope
Questions address alopecia patterns, scarring versus non-scarring hair loss, nail signs of systemic and dermatologic disease, and oral/genital mucosal lesions.
Core rules
- Alopecia areata: well-circumscribed patches, exclamation-mark hairs, yellow dots, peribulbar lymphocytic infiltrate; nonscarring.
- Androgenetic alopecia: follicular miniaturization; patterned distribution; topical minoxidil and finasteride.
- Telogen effluvium: diffuse shedding after stress, illness, or drug exposure; resolves.
- Scarring alopecias: lichen planopilaris, frontal fibrosing alopecia, discoid lupus; follicular dropout and loss of ostia.
- Nail signs: pitting (psoriasis), oil-drop sign, onycholysis, Beau lines, Mees lines, Hutchinson sign (melanoma).
- Mucosa: oral lichen planus, leukoplakia, candidiasis, aphthous ulcers, pemphigus, erythema multiforme/SJS, squamous cell carcinoma.
Worked example
A patient has a longitudinal pigmented nail band with pigment extending onto the cuticle (Hutchinson sign). Reasoning: this suggests nail matrix melanoma; biopsy of the matrix, not the nail plate, is required.
Traps
Not all nail pigmentation is melanoma; racial bands are common and benign. Scarring alopecia must be biopsied early to prevent irreversible loss. Oral leukoplakia requires biopsy to exclude dysplasia.