Primary Cardiac Synovial Sarcoma Originating From the Mitral Valve Causing Left Ventricular Outflow Tract Obstruction.

An 11-year-old boy was admitted with complaints of syncope and convulsion. Echocardiogram revealed a mass measuring 2 × 4 cm related to the mitral subvalvular apparatus. The mass, which appeared to be attached to the anterolateral papillary muscle, protruded into the left ventricular outflow tract causing intermittent obstruction. The patient underwent surgical excision of the mass. Pathology confirmed the diagnosis of primary synovial sarcoma. At six months following the operation, a small mass measuring 1 × 1 cm was detected in the left ventricle. The patient underwent reoperation consisting of radical resection of the subvalvular apparatus and mitral valve replacement. Histology confirmed that the mass was cardiac synovial sarcoma. One year after surgery, the patient is doing well.