Pigmentary, Hair, Nail and Mucosal Disorders
Domain 7 tests pattern recognition in pigment, hair, nail and mucosa, where cosmetic concern often hides serious disease.
Pigmentary
- Vitiligo: depigmented macules, Wood lamp accentuation, Koebner phenomenon; associated thyroid disease; NBUVB and topical calcineurin inhibitors.
- Melasma: symmetrical facial hyperpigmentation linked to hormones and UV; sunscreen plus hydroquinone-based therapy.
- Cafe-au-lait macules: six or more suggest neurofibromatosis type 1; ash-leaf spots suggest tuberous sclerosis.
Hair
- Androgenetic alopecia: patterned miniaturization (Hamilton/Ludwig); minoxidil and finasteride.
- Alopecia areata: well-circumscribed patches, exclamation-mark hairs, nail pitting; ophiasis carries worse prognosis.
- Telogen effluvium: diffuse shedding 2-3 months after a trigger. Scarring alopecias such as lichen planopilaris show loss of follicular ostia.
Nail and mucosa
- Longitudinal melanonychia: assess width, colour variation and Hutchinson sign; biopsy the matrix if suspicious.
- Psoriasis: pitting, oil spots, onycholysis. Onychomycosis needs KOH and culture.
- Oral leukoplakia is premalignant; oral lichen planus needs follow-up; candidiasis responds to antifungals.
Worked example
A 26-year-old woman reports diffuse hair shedding for 3 months after childbirth. Trichoscopy shows normal follicular ostia and increased telogen hairs without miniaturization. Diagnosis: telogen effluvium. Reasoning: timing, diffuse pattern and preserved ostia; reassure and correct iron and thyroid status.
Traps
Do not miss Hutchinson sign in nail pigmentation. Do not treat melasma with hydroquinone without photoprotection. Do not label scarring alopecia as telogen effluvium.