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Chronic Actinic Dermatitis — SCE Dermatology MCQ

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HardPhotobiologyChronic Actinic DermatitisSCE Dermatology

A 52-year-old man who is an avid sunbed user presents with a pruritic eczematous eruption on sun-exposed areas of his chest and forearms that develops within hours of UV exposure and resolves within days. His MED (minimal erythema dose) to UVA is markedly reduced. What is the most likely diagnosis?

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Correct answer: A — Chronic actinic dermatitis

Chronic actinic dermatitis (CAD), previously known as persistent light reactivity/actinic reticuloid, is characterised by chronic eczematous eruption on photo-exposed sites with markedly reduced MED to UVA (and often UVB and visible light). It predominantly affects middle-aged/elderly men. The key distinguishing feature is the persistent eczematous nature and reduced MED. Polymorphic light eruption is more common in young women and shows papulovesicular lesions with normal MED. Solar urticaria presents with immediate wheals within minutes. Drug photosensitivity should be excluded.

Reference: BAD 2019 Guidelines on Photodermatoses; NICE