Unusual Appearance of Mitral Annular Calcification Mimicking Intracardiac Tumor Prompting Early Surgery

Although mitral annular calcification (MAC) is usually easy to diagnose by transthoracic echocardiography, we experienced a rare case with MAC which looked like an intracardiac tumor. The patient who had been on chronic hemodialysis for 20 years was admitted to our hospital because of dyspnea. Transthoracic echocardiography showed a mass with severe calcification on the anterior mitral annulus and mean mitral gradient of 20 mm Hg. Because of the suspicion of the intracardiac calcified tumor that restricted mitral valve motion causing mitral obstruction, she underwent resection of the mass and mitral valve replacement. Pathological findings showed that the mass had a calcified envelope containing liquefied necrotic eosinophilic material with lympocytic infiltrate inside consistent with MAC. We should consider a possibility of MAC when we see a severe calcified mass attached to the mitral annulus in a patient on long-term hemodialysis.