A case of caseous calcification of the mitral annulus with mobile mass.

A 75-year-old woman had a 4-year history of hemodialysis and underwent aortic valve replacement for aortic valve stenosis one year previously. She was referred to our hospital to treat atrial fibrillation. Echocardiography at the initial visit incidentally revealed mitral annular calcification (MAC) involving the posterior mitral leaflet and mobile mass attached to this MAC. The high intensity echogenic mobile mass extended from the sub-valvular tissue to the papillary tendon. The differential diagnosis of this mass included a caseous calcification of the mitral annulus (CCMA), and intra-cardiac thrombus or tumor. Computed tomography imaging features were consistent with CCMA. Anticoagulation was administered for one month to rule out thrombus and to prevent systemic thromboembolism. The size of this mobile mass did not change but the severity of mitral regurgitation worsened from mild to moderate during the month. Surgical treatment was performed to prevent thromboembolism and treat mitral regurgitation. A biological mitral valve and tricuspid annular ring were implanted. The histopathologic examination of the excised mobile mass revealed fibrinous material with calcification. We report a case of CCMA that appeared in a short period of time, and the attached mobile mass was suggested to be the contents of CCMA. Learning objective: 1)A mobile high intensity echocardiographic mass consisting of fibrinous material with calcification is a characteristics feature of a caseous calcification of the mitral annulus (CCMA), and is suggested to be the contents of CCMA.2)Mitral regurgitation worsened over a short period in a patient with CCMA.3)CCMA with a mobile mass is extremely rare, and it is important to understand its clinical imaging features and clinical course.