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Allergic contact dermatitis — SCE Dermatology MCQ

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ModerateCutaneous allergyAllergic contact dermatitisSCE Dermatology

A 42-year-old hairdresser has a 9-month history of fissured erythematous plaques on the dorsal hands and fingertips. Emollients and intermittent topical corticosteroids give partial relief, but the eruption relapses within days of returning to work. Examination shows vesicles at the finger webs and periungual scaling; there is no palmar hyperkeratosis. What is the most appropriate investigation?

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Correct answer: D — Patch testing with a hairdressing allergen series

The chronic occupational pattern with vesicular hand dermatitis and relapse on exposure is most consistent with allergic contact dermatitis, so patch testing with an occupational series is the key investigation. Skin-prick testing is useful for immediate-type urticaria or rhinitis but does not diagnose delayed type IV contact allergy. Fungal culture, IgE testing and biopsy may be reasonable in selected mimics, but they would not identify the relevant workplace allergen.

Reference: BAD Guidelines for contact dermatitis; British Society for Cutaneous Allergy guidance