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Allergic contact cheilitis — SCE Dermatology MCQ

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HardCutaneous allergyAllergic contact cheilitisSCE Dermatology

A hairdresser has chronic cheilitis and hand eczema. Baseline patch tests are negative. She brings a leave-on lip balm, a rinse-off shampoo and concentrated bleach from work. Which extension best follows BAD patch-testing guidance?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: C — Test lip balm undiluted, shampoo diluted and omit concentrated bleach

Explanation lettering: C = shown as A · E = shown as B · B = shown as C · A = shown as E

B is correct. Exposure-directed testing complements the baseline series. A leave-on cosmetic is usually tested as supplied; a wash-off product requires a validated non-irritant dilution. Strong irritants such as concentrated bleach should not be occluded because an irritant burn can mimic allergy. A repeated open-application test can help with cosmetics when standard testing is equivocal, but it does not replace a properly selected series. Skin-prick testing assesses immediate hypersensitivity, not the delayed eczematous reaction suspected here. Relevance still requires exposure history and improvement with avoidance.

Reference: BAD guideline for contact dermatitis: https://doi.org/10.1111/bjd.15239