Caseous calcification of the mitral valve ring.

Mitral annular calcification (MAC) is found in 10% of patients older than 50 years of age, and represents deposition of calcium between the basal infero-lateral ventricular wall and the posterior leaflet of the mitral valve. Caseous calcification, formed from a mixture of calcium, cholesterol and fatty acids, is an uncommon variant found on echocardiography in 0.6% of patients with MAC. The characteristic echographic appearance is of a large echo-dense structure with echo-lucent center and smooth borders. Caseous MAC carries a benign prognosis despite its impressive appearance and should not be misdiagnosed as a more serious condition such as myocardial abscess or tumor.