Large obstructive cardiac myxofibrosarcoma is nearly invisible on transthoracic echocardiogram.

Malignant primary cardiac tumors are exceptionally rare, and the most common of these are sarcomas. We present a case of a patient who was found to have a large mass in the left atrium causing obstruction of mitral inflow. Only selected views on a transthoracic echocardiogram reveal the mass and its hemodynamic effect. Although the mass was sizeable, it could be easily overlooked on cursory review of the echocardiogram. After surgical resection, the mass was proven to be a myxofibrosarcoma. We review the etiologies and possible solutions for the imperfect sensitivity of transthoracic echocardiography for cardiac masses.