Primary cardiac
synovial sarcoma is a rare entity, arising from the pericardium or the chambers of the heart. It presents in the 4th decade of life with a striking male predisposition. We describe an unusual case of a 22-year-old female who presented with complaints of dyspnoea on exertion, palpitations, and
chest pain. Trans-thoracic echocardiography was suggestive of a cystic pericardial mass with
pericardial effusion anterior and lateral to the right ventricle. Computed tomography scan (CT scan) revealed thick-walled predominantly cystic lesion over the left ventricle with gross
pericardial effusion with internal septations. These findings were suggestive of an infected
pericardial cyst. Upon surgery, an adherent mass in the pericardial cavity was found which was not separable from the right heart structures, the great vessels, and the left ventricle. Biopsy was taken, histopathology was suggestive of spindle cell
neoplasm, and an immunohistochemistry analysis revealed
Transducin-like enhancer of split 1 (TLE 1)-positive malignant spindle cell tumour likely
synovial sarcoma. After surgery, the patient received serial adjuvant chemo-
radiation therapy. The
synovial sarcoma masqueraded as effusive
constrictive pericarditis, due to which it eluded preoperative diagnosis.