HCV infection and extrahepatic manifestations.

Hepatitis C virus infection is associated with various extrahepatic manifestations such as mixed cryoglobulinemia, membranoproliferative glomerulonephritis and porphyria cutanea tarda. The link between mixed cryoglobulinemia and hepatitis C virus infection is actually well known. Interferon alpha therapy decreases hepatitis C viremia and improves the clinical signs and biochemical abnormalities of cryoglobulinemia. The rare combination of hepatitis C and panarteritis nodosa has still not been confirmed. The sicca syndrome also seems to be associated with hepatitis C virus, but this is not the typical Sjogren's syndrome. It is not yet well established if hepatitis C virus plays a pathogenic role in the development of thyroid dysfunction and autoimmune thyroiditis. Probably interferon therapy may be implicated in the development in this and other extrahepatic manifestations of hepatitis C virus infection. Although an epidemiological association of hepatitis C with lichen planus, neuropathies and other diseases has been observed, the etiological role and the pathogenic involvement of the hepatitis C infection remains unclear. Extrahepatic clinical manifestations are frequently observed in hepatitis C virus patients and involve primarily the joints, muscles, and skin. The most frequent immunological abnormalities include mixed cryoglobulins, antinuclear antibodies, and anti-smooth muscle antibodies.