Porphyria cutanea tarda: cutaneous manifestations and management.

Porphyria cutanea tarda (PCT) is the most common porphyria and is caused by inhibition of hepatic uroporphyrinogen decarboxylase in the setting of iron overload and oxidative stress. Clinically, PCT presents with cutaneous photosensitivity, skin fragility, blistering and erosions on sun-exposed skin, hypertrichosis, dyspigmentation, milia, and dark urine. Because the skin findings may resemble other blistering disorders, including pseudoporphyria and other cutaneous porphyrias, recognition of the characteristic clinical pattern is important to prompt appropriate biochemical testing. Diagnosis is established by elevated plasma and urine porphyrins, typically with a predominance of uroporphyrin and heptacarboxyl porphyrins, while erythrocyte porphyrins are normal or only mildly elevated. Skin biopsy may support the differential diagnosis but is not specific for PCT. Management centers on treatment of the underlying disease with risk factor modification and iron reduction, most commonly by therapeutic phlebotomy, with low-dose hydroxychloroquine as an effective alternative in selected patients. Sun protection remains important until biochemical remission is achieved. Although blistering and skin fragility generally improve with treatment, chronic scarring and other cutaneous sequelae may persist. This review focuses on the cutaneous manifestations of PCT, diagnostic considerations in patients with blistering photosensitivity, and current approaches to management of both active disease and persistent skin findings.