RESUMEN
A 44-year-old male presented to our hospital with exertional dyspnea. Transthoracic echocardiography revealed a large cystic mass in the left atrium obstructing the mitral valve orifice. Transesophageal echocardiography during emergency operation showed a large cystic mass along with a solid part near the stalk. The mass was resected en bloc including the margin of the left atrium around the stalk. His hemodynamics improved immediately after the operation and the patient was discharged shortly with uneventful postoperative course. While intra cardiac cystic mass has some possible pathologies including malignancy, pathological examination of this tumor revealed a myxoma with large hematoma which had probably grown up rapidly. This tumor was successfully eradicated under the guide of both transthoracic and transesophageal echocardiography.