Idiopathic inflammatory myopathy of the antisynthetase (Jo-1) type associated with noncaseating granulomas.

The idiopathic inflammatory myopathies are a heterogeneous group of syndromes that share the finding of chronic muscle inflammation. Recently, serologic subtyping of autoantibodies found in patients with these syndromes has been used to identify distinct clinical entities. We describe a 36-year-old woman who, based on the findings of polymyositis documented by both electromyography and muscle biopsy, features of Raynaud's phenomenon, symmetric polyarthritis, "mechanic's hands," and Jo-1 antibody positivity, was considered to have the antisynthetase subset of idiopathic inflammatory myopathy. In addition, the patient had granulomatous synovitis, and noncaseating granulomas were found in a breast nodule. This is the first published report of granuloma formation in the antisynthetase syndrome.