A case of polymyositis in a chronic hepatitis C patient treated with peg-interferon-alpha 2b and ribavirin therapy.

Hepatitis C virus (HCV) infection may result in progression to chronic hepatitis, cirrhosis and hepatocellular carcinoma. Interferon-based treatment in patients with chronic hepatitis C may achieve viral clearance, and as a consequence improve liver histology and prevent progression to hepatocellular carcinoma. At present, the recommended therapy for chronic hepatitis C is peg-interferon-alpha (PEG-IFN-α) in conjunction with the oral nucleoside analog ribavirin. In the current study, we report a case of polymyositis associated with chronic hepatitis C following PEG-IFN-α and ribavirin therapy. The patient, a 64-year-old female who was treated with combination therapy, demonstrated elevated serum CPK, AST, ALT and LDH levels at 28 weeks after treatment onset. As there was an elevation of the serum HCV-RNA levels, combination treatment was ceased at 24 weeks. The patient had received IFN therapy twice previously (IFN-α 2a and IFN-α 2b with ribavirin therapy); however, no adverse side effects were observed. Further laboratory examination, muscle biopsy and imaging data suggested polymyositis, possibly triggered by the PEG-IFN-α treatment. The patient was subsequently administered prednisolone and the dose tapered over 7 months. As a result the polymyositis has remained in remission. Although many autoimmune diseases have been associated with IFN therapy, the development of polymyositis is extremely rare.