RESUMEN
A 27-year-old man presented with exertional dyspnea and productive cough as well as weight gain. Transthoracic echocardiography revealed severe right ventricular enlargement with moderate systolic dysfunction and a large right atrial mass protruding into the right ventricular cavity with severe functional tricuspid stenosis. An urgent surgical operation was done, and the tumor was totally excised. The histological findings were those of a biphasic tumor, consistent with synovial sarcoma. This was also confirmed by an immunohistochemistry panel. The patient's chest CT scan showed multiple small peripheral nodules, suggestive of lung metastases. Chemotherapy was administered and several months afterwards, the patient was asymptomatic with no residual mass on echocardiography