Porphyria Cutanea Tarda — RACP Adult Medicine MCQ

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ModerateDermatologyPorphyria Cutanea TardaRACP Adult Medicine

A 40-year-old woman with known porphyria cutanea tarda (PCT) presents with blistering on the dorsal hands and face after sun exposure. She has a history of hepatitis C and iron overload. What is the first-line treatment for PCT?

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Correct answer: B — Sunscreen alone

PCT is the most common porphyria, caused by deficiency of uroporphyrinogen decarboxylase (UROD) in the liver. It is triggered by iron overload, HCV, alcohol, oestrogen, and HIV. First-line treatment is regular phlebotomy (500 mL every 2 weeks until ferritin <20 µg/L and haemoglobin minimum ~120 g/L). An alternative (particularly when phlebotomy is not tolerated) is low-dose hydroxychloroquine (100–200 mg twice weekly), which promotes porphyrin excretion. Treating the underlying HCV with DAAs also helps resolve PCT. Strict sun avoidance and protection are essential adjuncts.

Reference: eTG – 2025 – Haematology; eTG – 2025 – Dermatology