Surgery and Proton Beam Therapy for Mediastinal Extraskeletal Osteosarcoma.

Extraskeletal osteosarcoma (ESOS) arising from the mediastinum is a rare malignant tumor and associated with a poor prognosis. We present the case of a 73-year-old man with a hoarseness. Imaging studies revealed a large calcified tumor of the median mediastinum. Surgery was performed, but complete resection was impossible and approximately two thirds of the tumor was excised. The tumor was diagnosed pathologically as ESOS. Proton beam therapy has been performed on the remaining lesion, and the patient is alive without tumor regrowth after 29 months. This case report documents a mediastinum ESOS successfully treated successfully with surgery and postoperative proton therapy.