Malignant fibrous histiocytoma of the heart presenting as an atrial myxoma.

A 37-year-old woman presented with signs and symptoms suggestive of mitral stenosis and insufficiency. Subsequent evaluation demonstrated a left atrial tumor which was suspected clinically and at the time of initial surgery to be an atrial myxoma. Histologic examination revealed that the tumor was actually a malignant fibrous histiocytoma. Despite near total removal at surgery and subsequent radiotherapy, the tumor recurred within six months in the left atrium. Re-excision was followed by a third recurrence in the same site.