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

Background: 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. Case presentation: 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. Conclusions: 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.