[Association between polymyositis and hepatitis C infection. Treatment-related difficulties].

Introduction: Chronic hepatitis C virus infection is often associated with various auto-immune disorders. We report four cases of an association between polymyositis and hepatitis C virus infection. The course and the difficulties of therapy are discussed.

Exegesis: Among 510 consecutive patients infected by viral hepatitis C, we report four cases of polymyositis. Corticosteroids increased serum alanine aminotransferase levels in two cases, leading to severe liver injury in one patient. Worsening of polymyositis under interferon-alpha therapy was observed in one case. Clinical and biological stability were reported in another case. Aggravation of polymyositis with severe muscle weakness and dyspnea occurred in two patients after disruption of interferon-alpha treatment. Intravenous gamma globulins subsequently improved their condition, without biological worsening of viral hepatitis.

Conclusion: These observations suggest an association between hepatitis C virus infection and polymyositis. Because corticosteroids can induce adverse effects in the liver, intravenous gamma globulins could be used for the treatment of this particular form of polymyositis.