Sclerosing thymoma with extensive ossification and myasthenia gravis: an extremely rare case in the anterior mediastinum.

Sclerosing thymoma is a rare variant of thymomas, recently recognized in pathology. Since its first description in 1994, only 15 cases have been reported. Furthermore, osseous metaplasia in sclerosing thymoma is an even unusual characteristic. To date, only 7 such cases have been described, while half of them show the symptom of myasthenia gravis. Herein we present a 57-year-old female with ossifying sclerosing thymoma and myasthenia gravis, which is the first case in literature of type B3 sclerosing thymoma with extensive ossification and myasthenia gravis. In consideration of its rarity, awareness of the possible occurrence of extensive ossification and sclerosis in thymomas helps to avoid a diagnostic pitfall, especially in mediastinoscopic biopsy specimens.