Cancer-associated myositis in the presence of anti-Jo1 autoantibodies and the antisynthetase syndrome.

We describe 3 patients with inflammatory myositis in association with a neoplasm whose serum also contained anti-Jo1 antibodies, one of which presented characteristic features of the antisynthetase syndrome. No patient had a rash, and muscle biopsy was suggestive of polymyositis in all 3. Immunohistochemistry confirmed the diagnosis of polymyositis in the single patient with sufficient tissue available. Our patients remind us that the presence of antisynthetase antibodies (and even antisynthetase syndrome) in a patient with inflammatory myositis does not preclude the diagnosis of cancer-associated myositis.