Hepatitis C and porphyria cutanea tarda.

Porphyria cutanea tarda (PCT) is a clinical manifestation of decreased uroporphyrinogen decarboxylase (UPD) activity. Multiple endogenous and exogenous factors have been implicated in inducing PCT in genetically predisposed patients. The most recent is the RNA virus hepatitis C (HCV), which is transmitted via blood exposure. The mechanism of action in HCV-induced PCT is unknown but produces the same clinical, laboratory, and histopathologic changes seen in other forms of sporadic PCT. Therefore, patients presenting with PCT clinically should be tested serologically for antibodies against HCV and patients with HCV should be monitored for signs and symptoms of PCT.