Concomitant polymyositis and myasthenia gravis reveal malignant thymoma. A case report and review of the literature.

The frequency of thymona associated with autoimmune diseases has been reported to be increased, with 50% of thymoma patients also having myasthenia gravis (MG). Other autoimmune disorders, such as autoimmune erythroblastopenia and polymyositis (PM), have been less frequently associated with thymoma. The association of MG and PM with thymoma is rare. We here report the case of a 66-year-old woman whose concomitant MG and PM revealed malignant thymoma and review the other published cases of this association.