Primary mediastinal synovial sarcoma with transdiaphragmatic extension presenting as a pericardial effusion.

Synovial sarcoma is a distinctive soft tissue neoplasm, most commonly seen in the extremities of young adults. Mediastinal synovial sarcoma is a well-documented entity; however, in many cases, the differentiation between this and other spindle cell tumours may be difficult, especially in monophasic tumours. Unlike most pleuropulmonary synovial sarcomas which are well circumscribed, mediastinal tumours are often infiltrative and resection may not be adequate, leading to a high rate of recurrence. We present a 49-year-old man with a primary pericardial synovial sarcoma, with transdiaphragmatic intra-abdominal extension, which clinically, radiologically and grossly mimicked a tuberculous pericarditis.