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Alopecia Areata — SCE Dermatology MCQ

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HardHair DisordersAlopecia AreataSCE Dermatology

A 68-year-old woman with alopecia areata affecting >50% of her scalp is considering treatment with topical immunotherapy. What is the mechanism of action of diphenylcyclopropenone (DPCP) in alopecia areata?

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Correct answer: E — Contact sensitisation inducing an allergic contact dermatitis that modulates the perifollicular immune response

Topical immunotherapy with DPCP (diphenylcyclopropenone) works by deliberately inducing allergic contact dermatitis on the scalp. The resulting T-cell-mediated immune response is thought to modulate the pathogenic perifollicular lymphocytic infiltrate ('swarm of bees') that attacks the hair follicle in alopecia areata, possibly through antigenic competition or altered cytokine milieu. The patient is first sensitised to DPCP on a small area, then increasing concentrations are applied to maintain a mild eczematous reaction. It is most effective for extensive alopecia areata (>50% scalp involvement) with reported response rates of 40-60%.

Reference: BAD 2012 Alopecia Areata Guidelines; BJD