Hair, Nail and Mucosal Disorders
Hair
Alopecia areata (well-circumscribed patches, exclamation-mark hairs, nail pitting), androgenetic alopecia (patterned, miniaturization), telogen effluvium (diffuse shedding after stress), and scarring alopecias (lichen planopilaris, frontal fibrosing alopecia, discoid lupus). Trichoscopy helps: yellow dots, black dots, broken hairs.
Nails
Onychomycosis (distal subungual, KOH/culture), psoriasis (pitting, oil spots), lichen planus (longitudinal ridging, pterygium), and melanoma (Hutchinson sign). Nail biopsy is indicated for unexplained longitudinal melanonychia.
Mucosa
Oral lichen planus, aphthous ulcers, leukoplakia (premalignant), and pemphigus vulgaris. Vulvar and penile lesions require biopsy when persistent.
Traps
- Missing frontal fibrosing alopecia because it mimics androgenetic alopecia; look for eyebrow loss and band-like scarring.
- Treating onychomycosis without confirming organism.
- Overlooking mucosal melanoma in persistent pigmented lesions.
Rule of thumb
For hair loss, ask: scarring vs non-scarring (loss of ostia on trichoscopy indicates scarring).
Worked example
A postmenopausal woman with receding frontal hairline and eyebrow loss: suspect frontal fibrosing alopecia; biopsy shows lymphocytic scarring and treat with anti-inflammatory therapy.