Primary synovial sarcoma of the mitral valve.

Primary cardiac synovial sarcoma is a rare malignancy, comprising approximately 5% of cardiac sarcomas and less than 0.1% of all primary cardiac tumors. Herein, we describe a synovial sarcoma arising on the anterior mitral leaflet in a 66-year-old man. The histopathologic diagnosis was supported by the immunohistochemical profile and the presence of the SYT-SSX1 fusion transcript identified by molecular genetic studies.