Abstract
A 57-year-old man was admitted to our hospital with cardiomegaly on a chest roentgenogram. A mediastinal tumor was observed during a chest computed tomographic scan and the patient was diagnosed with pericardial synovial sarcoma as a result of a tumor biopsy. Surgery, radiotherapy and chemotherapy were carried out, and although the tumor temporarily decreased in size, it subsequently increased and the patient died approximately 3 years following the initial medical examination. Most synovial sarcomas commonly occur in the vicinity of the joints of the extremities. Therefore, we herein report a rare case of synovial sarcoma which occurred in the pericardium.