Nonsarcoid granulomatous myopathy: Two cases and a review of literature

Granulomatous myopathy is an uncommon skeletal muscles disorder. It can develop in association with other granuloma-forming diseases and is then considered a secondary myopathy or, less frequently, a primary disorder for which no etiology is identified. Studies of granulomatous myopathies have focused on examining the differences between primary and secondary diseases. Herein, we describe two cases of nonsarcoid granulomatous myopathies, for which diagnostic work-up did not reveal an underlying granuloma-causing pathology. The patients exhibited similar histopathological characteristics in skeletal muscle biopsies. However, they had different clinical presentations and therapeutic responses. Specifically, one patient had distal muscle weakness with a poor response to immunosuppressive treatment, whereas the other had a more proximal muscle weakness distribution and a very good response to treatment with corticosteroids and azathioprine, resulting in remission. More studies are warranted to further characterize the clinical course and effect of different treatment modalities on nonsarcoid granulomatous myopathy.