A case of thymoma-associated myasthenia gravis accompanied with myositis showing the clusters of histiocyte along the fascicles in perimysium.

Patients with myasthenia gravis (MG) often have other autoimmune disorders. However, the coexistence of MG and myositis is rare. Here, we report a case of a 77-year-old woman who developed mild fatigable muscle weakness and diplopia in 3 months.