Primary left atrial myxosarcoma.

A patient in whom rapidly progressive congestive heart failure developed due to the presence of a left atrial myxosarcoma is described. The histologic picture is consistent with the hypothesis that cardiac myxoid tumors are neoplasms derived from undifferentiated cells found in the endocardium. Unfortunately, most cardiac malignancies are detected too late for curative resection, and palliation remains the mainstay of therapy.