Alopecia and hair disorders in children — formative SAQs

SAQ 1 — The smooth bald patch (10 marks, 15 minutes)

An eight-year-old girl is brought by her mother, who has noticed a coin-sized, completely bald, smooth patch behind the left ear over three weeks. The overlying skin is normal with no scale or redness, and at the edge there are a few short hairs that taper to a fine point. Dermoscopy shows yellow dots, black dots and exclamation-mark hairs. There is no lymphadenopathy. ^[1]

a) What is the most likely diagnosis, and which single bedside feature most reliably distinguishes it from tinea capitis? (2 marks) ^[12]

b) Name the key autoimmune association and the screening test you would perform. (2 marks) ^[4]

c) Outline the stepwise management for limited patchy disease, naming the first-line topical agents and giving the intralesional triamcinolone acetonide concentration and dosing interval you would use for a discrete patch. (4 marks) ^{[1] [2]}

d) List four clinical features that predict a poorer prognosis. (2 marks) ^[4]