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Photoallergic Dermatitis — SCE Dermatology MCQ

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HardPhotobiologyPhotoallergic DermatitisSCE Dermatology

A 40-year-old woman presents with a photodistributed eczematous eruption affecting her face, V-neck, and forearms. She applies a new sunscreen before sun exposure. Photopatch testing shows a positive reaction to Oxybenzone (benzophenone-3) at the irradiated site but not the non-irradiated site. What does this indicate?

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Correct answer: D — Photoallergic contact dermatitis to Oxybenzone

The best answer is “Photoallergic contact dermatitis to Oxybenzone”. Eczema treatment is selected by site and severity, with topical corticosteroid or calcineurin-inhibitor safety, infection, adherence, contact allergy and psychosocial effects considered before escalation. The alternatives “Phototoxic dermatitis caused by oxybenzone exposure”, “Ordinary allergic contact dermatitis without photoactivation”, “Polymorphic light eruption unrelated to the sunscreen”, “Chronic actinic dermatitis without allergen dependence” are clinically adjacent possibilities, but they do not fit the defining morphology, distribution, histopathology, risk signal or management sequence in this stem.

Reference: NICE CG57 atopic eczema recommendations: https://www.nice.org.uk/guidance/cg57/chapter/Recommendations