Mediastinal Primary Synovial Sarcoma With Postoperative Pericardial Recurrence in a Previously Treated Angiofibroma

Synovial sarcoma is a malignant soft tissue tumor that often occurs near the limb joints. Here, we report a case of a patient with a synovial sarcoma that occurred in the mediastinum. The initial pathological diagnosis was suspected angiofibroma after surgical resection. After surgery, the tumor recurred in the pericardium and caused cardiac tamponade. Pericardial fenestration was performed and the patient was diagnosed with synovial sarcoma. The final diagnosis was the postoperative pericardial recurrence of the mediastinal synovial sarcoma. It is important to consider follow-up on the basis of the malignant tumor, especially if the disease is rare.