Malignant fibrous histiocytoma of the left atrium: A rare cause of postcapillary pulmonary hypertension

This case report describes a rare form of pulmonary hypertension caused by an intracardiac tumor in a patient presenting with dyspnea and systemic emboli. Failure to diagnose this tumor by transthoracic echocardiogram in the setting of a remarkably abnormal ventilation-perfusion scan opened up a broader differential diagnosis of central pulmonary vascular lesions. This is the first report showing the usefulness of MRI in diagnosing the cause of postcapillary pulmonary hypertension. This report also highlights the fact that transthoracic echocardiogram can miss the diagnosis of a left atrial tumor. Therefore if clinical suspicion for this condition is high and poor visualization of the left atrium is noted, a transesophageal echocardiogram should be performed. It is also important to consider that absent to virtually absent perfusion to one lung as was detected by lung ventilation and perfusion scan should raise the possibility of a central compression, occlusion, coarctation, or atresia of the main pulmonary artery, as well as complete obstruction of the pulmonary venous drainage. It seems reasonable to suggest that MRI of the lung and mediastinum should be the diagnosis test of choice over invasive pulmonary arteriography in situations with complete unilateral perfusion defects.