skip to main content

Phytophotodermatitis — SCE Dermatology MCQ

Instant feedback + full explanation. One question, done properly.

HardPhotobiologyPhytophotodermatitisSCE Dermatology

A 25-year-old woman presents with vesicular eruption on her lower legs in a linear arrangement following contact with a plant while walking through meadows. The eruption developed 24 hours after sun exposure following the plant contact. There is hyperpigmentation without prominent erythema. What is the diagnosis?

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

Reveal the answer and explanation

Correct answer: D — Phytophotodermatitis from plant psoralen exposure followed by ultraviolet A

The best answer is “Phytophotodermatitis from plant psoralen exposure followed by ultraviolet A”. The diagnosis follows the defining morphology, distribution, histopathology and time course; management changes when red flags, scarring, systemic disease or malignancy risk are present. The alternatives “Allergic phytocontact dermatitis without ultraviolet dependence, within an appropriate UK pathway”, “Irritant plant dermatitis confined to contact pressure”, “Polymorphic light eruption without plant exposure, after specialist assessment”, “Photoallergic dermatitis caused by systemic medication, when the full phenotype supports it” are clinically adjacent possibilities, but they do not fit the defining morphology, distribution, histopathology, risk signal or management sequence in this stem.

Reference: British Association of Dermatologists clinical resources: https://www.bad.org.uk/