A Mass Filling the Right Atrium: A Case of Primary Cardiac Rhabdomyosarcoma.

A 43-year-old woman presented with worsening shortness of breath and lower-extremity edema. Echocardiography and computed tomography showed obstruction of blood flow due to a mass filling the right atrium. Emergency surgery was performed for circulatory failure. Primary cardiac rhabdomyosarcoma was diagnosed based on a histological examination. The patient died about two months after the diagnosis despite surgical excision and radiation therapy. The poor prognosis may have resulted from the grossly incomplete removal of the tumor and chemotherapy intolerance. We herein report a case of primary cardiac rhabdomyosarcoma filling the right atrium and offer possible reasons for the poor prognosis.