Cardiac Sarcoma Arising From Malignant Transformation of a Preexisting Atrial Myxoma.

A 49-year-old man presented with shortness of breath on exertion, orthopnea, and chest pain. On transthoracic echocardiography, a myxomatous mass was seen in the left atrium. A diagnosis of atrial myxoma was made and the patient underwent urgent surgical intervention. At operation, the mass, which extended into the anterior leaflet of the mitral valve, was excised. Histopathologic examination showed a primary cardiac sarcoma arising within a preexisting atrial myxoma. The patient received no further treatment and died 7 months postoperatively. We report the first case of a malignant transformation of an atrial myxoma to a cardiac sarcoma.