Myoepithelial carcinoma in the mediastinum involving the left atrium.

We report a case of a 56-year-old male who presented with typical atrial flutter and was diagnosed with a large mediastinal mass, posterior to the ascending aorta, noted within the left atrium, compressing the superior vena cava and right superior pulmonary vein, and measuring >9.0 cm at its greatest diameter. Histopathological studies showed a myoepithelial carcinoma. The patient underwent tumor debulking and radiation therapy. This is the first report of a mediastinal myoepithelial carcinoma involving cardiac chambers.