Massive primary cardiac synovial sarcoma of the left atrium: a case report

Synovial sarcomas are tumors typically located in the extremities and characterized by a t(X;18)(p11.2;q11.2) chromosomal translocation. With only around 100 cases reported in the literature, cardiac synovial sarcomas are extremely rare.

We describe a case of a 59-year-old male who presented to his primary care physician with chest pain, palpitations, and dyspnea and was diagnosed with atrial flutter. Following atrial ablation, a transthoracic echocardiogram incidentally revealed a 5.5 × 5.0 cm heterogeneous mass. Further workup found a heterogeneous mass with mild fluorodeoxyglucose uptake that was abutting the left atrium, left ventricle, and left pulmonary veins. The tumor was resected and confirmed to be a monophasic synovial sarcoma with a SS18-SSX gene fusion. Four months post-operative, the patient had recovered well from surgery. He is currently undergoing concurrent radiation and chemotherapy.

Due to the rarity of this tumor, guidelines on diagnosis and treatment come only from case reports. Our case describes a primary cardiac synovial sarcoma arising from the left atrium in the atrioventricular groove in which diagnosis of atrial flutter preceded detection of the mass.