Anti-liver/kidney microsome-1-positive chronic hepatitis C with type I cryoglobulinemia responding to interferon

A 53-year-old man was admitted to our hospital for close examination of his liver. Serum hepatitis C virus (HCV) RNA and anti-liver/kidney microsome (LKM) 1 were positive. Benign monoclonal gammopathy and type I cryoglobulinemia (both of IgG lambda class) which are rarely seen in association with chronic hepatitis C, were found to be present. Interferon therapy was given, resulting in the disappearance of both HCV-RNA and type I cryoglobulin in the blood. We propose a hypothesis that the primary cause of anti-LKM-1-positive chronic hepatitis C is HCV infection which triggers secondary autoimmune phenomena presenting anti-LKM-1 and cryoglobulinemia.