Mesothelial/monocytic incidental cardiac excrescence in autoimmune disease

From the archives of MD Anderson Cancer Center. Mesothelial/monocytic incidental cardiac excrescence with a review of the literature

Mesothelial/monocytic incidental cardiac excrescence (MICE) is a rare benign lesion composed of monocytes and mesothelial cells that is most often encountered during cardiothoracic surgery. We describe a case in a 71-year-old man with known aortic valve stenosis who presented with gradual onset dyspnea over a few weeks, made worse with minimal exertion. A transesophageal echocardiogram revealed severe aortic stenosis and mild pericardial effusion. The patient underwent aortic valve replacement, coronary artery bypass, and amputation of the left atrial appendage. Histological examination of a 0.8 cm blood clot received along with the atrial appendage showed an aggregation of bland cells with features of monocytes associated with small strands and nodules of mesothelial cells, fat cells, fibrin and a minute fragment of bone. Immunohistochemical analysis showed that the monocytic cells were positive for CD4 and CD68 (strong) and negative for calretinin and keratin. By contrast, the mesothelial cells were positive for calretinin and keratin and negative for all other markers. In sum, the morphologic and immunohistochemical findings support the diagnosis of MICE. Based on our review of the literature, about 60 cases of MICE have been reported previously which we have tabulated. We also discuss the differential diagnosis.

Mesothelial or monocytic incidental cardiac excrescence on anterior leaflet of mitral valve

Mesothelial or monocytic incidental cardiac excrescence (MICE) is a rare, benign lesion composed of a mixture of mesothelial and inflammatory cells, histiocytes and fibrin without a vascular network usually accidentally found during cardiac surgery or after cardiac catherization. We report the case of a 45-year-old man admitted for suspected myxoma on the mitral valve. The lesion was removed via a minimally invasive video-assisted approach, without compromising the valve competency. The histopathological exam led to the diagnosis of MICE. The 2-year follow-up echocardiography confirmed normal mitral function without recurrence. Most of the cases were treated concomitantly to other cardiac procedure, lesions were more frequently founded in the left cardiac chambers or valves, our experience suggest that these lesions should be safely treated alone by surgical removal, to prevent embolic events.