Pericardial malignant mesothelioma: case report and discussion of immunohistochemical and histochemical findings.

An extremely rare case of malignant mesothelioma of the pericardium is reported. The tumor appeared to be the biphasic type of diffuse malignant mesothelioma which present many small to fine lipid droplets in the cytoplasm, particularly that of the epithelial cell, and a positive immunohistochemical reaction with antibodies to low molecular weight cytokeratin (45-50 kDa) in all of the tumor cells. The literature is also reviewed and the presence of lipid droplets and the importance of the immunohistochemical positivity to low molecular weight cytokeratin for differential diagnosis from other malignant tumors, such as invasive adenocarcinoma or primary sarcoma of the pleura, or soft tissue sarcoma involving the pleura is discussed.