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Porphyria Cutanea Tarda — SCE Dermatology MCQ

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HardBlistering DiseasesPorphyria Cutanea TardaSCE Dermatology

A 35-year-old woman presents with a blistering eruption after drinking alcohol. She has previously been well. She has hypertrichosis of the face and blistering on the dorsum of her hands. Urine porphyrins show markedly elevated uroporphyrin and heptacarboxyl porphyrin. What investigation should be performed to identify the most common acquired trigger?

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Correct answer: B — Hepatitis-C-virus and HIV serology, iron studies and liver assessment

The best answer is “Hepatitis-C-virus and HIV serology, iron studies and liver assessment”. The level of blister cleavage and the distribution of immunoreactants distinguish intraepidermal pemphigus-pattern disorders from subepidermal autoimmune blistering diseases. The alternatives “Antinuclear and extractable-nuclear-antigen antibody testing, within an appropriate UK pathway”, “Total IgE and allergen-specific sensitisation testing, after clinicopathological correlation”, “Thyroid function and thyroid-autoantibody testing, after specialist assessment”, “Calcium, phosphate and parathyroid-hormone testing, 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: BAD pemphigus and blistering disease information: https://www.bad.org.uk/pils/pemphigus-vulgaris