[Undifferentiated pleomorphic sarcoma in the left atrium; report of a case].

Primary cardiac sarcomas are rare. A 41-year-old woman complaining of dyspnea was admitted to our hospital. Echocardiography and computed tomography (CT) showed a primary cardiac tumor in the left atrium. During surgery, the tumor was noted to be arising from the anterior wall of the left atrium, under the aortic sinuses. Histological and immunohistochemical studies revealed an undifferentiated pleomorphic sarcoma. Eleven months later, echocardiography and CT showed recurrence of the cardiac sarcoma in the left atrium. The patient underwent wide resection of the left atrium and mitral valve replacement because the tumor extended to the mitral valve leaflet. The patient died 3 months after the 2nd surgery because of the 2nd recurrence of the cardiac sarcoma. Although most tumors that develop in the left atrium are benign myxomas, preoperative differential diagnosis is important. It is especially necessary to suspect a sarcoma in the case of a non-septal orgin of the mass.