Lesion of aggregated monocytes and mesothelial cells: mesothelial/monocytic incidental cardiac lesion.

[acute rheumatic fever]

A 58 -year -old woman with a history of childhood acute rheumatic fever and resultant mitral valve stenosis was admitted to our cardiovascular surgery clinic complaining of tachycardia , dyspnea , and chest pain . After clinical and radiological findings were evaluated , mitral valve replacement , tricuspid De Vega annuloplasty and plication , and resection of giant left atrium were performed . Atrial thrombus was removed from the top of the left atrial wall . Operation material considered as thrombus was sent to a pathology laboratory for histopathological examination . It was diagnosed with mesothelial /monocytic incidental cardiac lesion (cardiac MICE ). Microscopic sections revealed that morphological features of the lesion were different from thrombus . The lesion was composed of a cluster of histiocytoid cells with abundant cytoplasm and oval shaped nuclei and epithelial-like cells resembling mesothelial cells within a fibrin network . Epithelial-like cells formed a papillary configuration in the focal areas . Mitotic figures were absent . Here we present a case which was incidentally found in a patient who underwent mitral valve replacement surgery , as a thrombotic lesion on the left atrium wall .