Granulomatous Myositis Associated with Extremely Elevated Anti-striated Muscle Antibodies in the Absence of Myasthenia Gravis.

Granulomatous myositis is a rare disease that predominantly results in proximal muscle weakness in the upper and/or lower extremities. As it can resemble other inflammatory myopathies, it is important to obtain a muscle biopsy to make the underlying diagnosis. We report the first case of granulomatous myositis associated with extremely elevated anti-striated muscle antibodies in a 69-year-old Caucasian woman. Granulomatous myositis has been associated with various autoimmune, infectious, rheumatologic, vasculitis, and oncologic disorders, and several antibodies have previously been reported to be associated with it. However, to the best of our knowledge, this is the first report where extremely elevated anti-striated muscle antibodies were found to be associated with granulomatous myositis in the absence of myasthenia gravis. The treatment of granulomatous myositis revolves around the use of corticosteroids, steroid-sparing immunosuppressive agents, and newer biologics.