Hepatitis C virus infection, inflammatory myopathy, and pulmonary fibrosis: are they related?

We describe the clinical findings, laboratory and ancillary studies, and histopathologic findings of 2 patients with hepatitis C virus infection who developed inflammatory myopathy and interstitial lung disease. A review of pertinent literature revealed several other patients with a similar cluster of clinical manifestations. The inflammatory myopathy in the cases reported here was atypical and distinct from that found in the anti-synthetase syndrome because it was characterized by mild or intermittent elevation of creatine phosphokinase, absence of anti-JO1 antibodies, and excellent response to oral corticosteroids. Thus, this report supports the hypothesis that hepatitis C virus infection may cause both inflammatory myopathy and pulmonary fibrosis. We suggest that evaluation for hepatitis C virus infection should be pursued in all patients with inflammatory myopathy and pulmonary fibrosis irrespective of anti-JO1 status. We further suggest that hepatitis C should be considered as another cause of myositis and interstitial lung disease in addition to the anti-synthetase syndrome.