Primary undifferentiated sarcoma of the pericardium.
A 60-year-old woman was found to have a pericardial mass on two-dimensional echocardiography and computerized tomography. At autopsy, there was a large tumor arising from the epicardial surface of the left ventricle. The tumor encircled the great arteries and invaded the wall of the pulmonary artery. Microscopic examination showed features of an undifferentiated sarcoma.