Left atrial mass. Thrombus mimicking myxoma

With newer diagnostic methods, clinical (pre-mortem) recognition of atrial tumors is becoming more frequent. Thrombi are the most common cause of mass lesions within the atria, but myxomas and other neoplasms must be considered in the differential diagnosis. Criteria have been proposed to differentiate between the various types of atrial masses, but the reliability of these criteria is uncertain. We describe a patient in whom diagnostic workup of unexplained atrial fibrillation revealed a left atrial mass strongly suggestive of myxoma. The surgical specimen was also grossly consistent with myxoma, but histologic examination of the mass showed it to be a large thrombus.