Porphyria cutanea tarda: Recent update.

Porphyria cutanea tarda (PCT) is the most common human porphyria, due to hepatic deficiency of uroporphyrinogen decarboxylase (UROD), which is acquired in the presence of iron overload and various susceptibility factors, such as alcohol abuse, smoking, hepatitis C virus (HCV) infection, HIV infection, iron overload with HFE gene mutations, use of estrogens, and UROD mutation. Patients with familial or type II PCT due to autosomal dominant UROD mutation also require other susceptibility factors, as the disease phenotype requires hepatic UROD deficiency to below 20% of normal. PCT clinically manifests with increased skin fragility and blistering skin lesions on sun exposed areas. The common age of presentation is 5th to 6th decade and occurs slightly more commonly in males. Although mild liver biochemical profile are common, advanced fibrosis and cirrhosis with hepatocellular carcinoma (HCC) can occasionally develop. Screening for HCC using ultrasound examination is recommended in PCT patients, especially with cirrhosis and advanced fibrosis. PCT is effectively and readily treatable with the use of either repeated phlebotomy or use of 100 mg hydroxychloroquine orally twice a week, and both the treatments are equally effective and safe. With the advent of new or direct antiviral agents for HCV infection, treatment of concomitant HCV has become safer and effective. Data are emerging on the benefit of these drugs as monotherapy for both PCT and HCV. After the achievement of remission of PCT, there remains a potential for relapse, especially when the susceptibility factors are not adequately controlled. Scanty data from retrospective and observational studies shows the relapse rate to be somewhat higher after remission with low-dose hydroxychloroquine as compared to phlebotomy induced remission. Future studies are needed on exploring mechanism of action of 4-aminoquinolines, understanding interaction of HCV and PCT, and relapse of PCT on long-term follow-up.