Alopecia and hair disorders in children — branching viva

Opening — framing the problem

The examiner begins: an eight-year-old has a three-week history of a coin-sized, completely bald, smooth patch behind the left ear, with no scale, no redness and a few tapering exclamation-mark hairs at the edge. Talk me through your approach. [1]

I would frame this as alopecia areata. The completely smooth, non-scaly bald patch with exclamation-mark hairs at the edge is the signature of an autoimmune attack on the anagen hair bulb, and the dermoscopy I would expect to see, yellow dots, black dots and short regrowing vellus hairs, supports it. The absence of scale, broken stubs and lymphadenopathy distinguishes it from tinea capitis at the bedside. [1]

Branch A — the autoimmune associations

What is the key association, and what would you screen for? [4]

The key association is with other autoimmune disease, most importantly autoimmune thyroid disease, and I would screen thyroid function, with thyroid antibodies where clinically indicated. I would also ask about vitiligo, type 1 diabetes and a family history of autoimmune disease, and note that the condition is more common in Down syndrome. These associations are why thyroid screening is built into the work-up even when the child is clinically well. [4]

Branch B — the stepwise management

How would you manage limited patchy disease? [1]

For limited patchy disease I would start a potent or ultrapotent topical corticosteroid, with or without topical minoxidil five per cent. For a few discrete patches I would use intralesional triamcinolone acetonide at around five to ten milligrams per millilitre, in small volumes per site, repeated every four to six weeks. I would escalate to topical immunotherapy with diphenylcyclopropenone or squaric acid dibutylester for extensive or active disease, add a short oral corticosteroid course to halt rapid shedding, and reserve systemic therapy, oral minoxidil and JAK inhibitors for refractory disease under dermatology guidance. [1] [2]

Branch C — the prognostic features

Which features predict a worse outcome? [4]

A worse prognosis goes with the ophiasis pattern, with the totalis and universalis patterns, and with the features of atopy, early childhood onset, nail involvement, long duration before treatment, extensive involvement, and a family history. Limited patchy disease, by contrast, has a good prognosis with a high rate of spontaneous or treatment-assisted regrowth. I would set honest expectations with the family from the outset. [4]

Branch D — the pivot to trichotillomania

Now a twelve-year-old has an irregular patch over the crown with hairs broken to wildly varying lengths and a completely normal scalp, and he denies pulling. What is this and how do you manage it? [8]

This is trichotillomania, a body-focused repetitive behaviour classified with the obsessive-compulsive and related disorders. The hairs of wildly varying lengths on a normal scalp, with none of the exclamation-mark hairs of alopecia areata, give it away. First-line management is habit-reversal and cognitive behavioural therapy, because the behavioural driver must be addressed for any treatment to hold. Pharmacotherapy with N-acetylcysteine, a selective serotonin reuptake inhibitor or clomipramine is an adjunct for severe cases, but the Cochrane review found only modest evidence, so it is not first-line. I would also ask about hair eating, because trichophagy can form a trichobezoar. [8] [9]

Closing — distinguishing tinea capitis

Finally, a child has a bald patch with broken stubs, black dots and occipital lymphadenopathy. How do you tell it from alopecia areata, and what is the trap? [12]

The scale, the broken stubs, the black dots and the lymphadenopathy point to tinea capitis rather than alopecia areata, and I would confirm it with potassium hydroxide microscopy of a plucked hair looking for branching septate hyphae. The trap is treating a scaly fungal patch as alopecia areata with a topical steroid, which causes tinea incognito and allows the fungus to spread. Tinea capitis always needs an oral antifungal, because no topical agent reaches the hair shaft. [12]