An autopsy case of a malignant pericardial mesothelioma in a Japanese young man

An autopsy case of a malignant pericardial mesothelioma in a 27-year-old man with no history of exposure to asbestos is reported. He was admitted for heart failure due to pericardial effusion of unknown origin and surgically drained, but later died. The diagnosis of a malignant pericardial mesothelioma was made on the basis of histologic, immunohistochemical and ultrastructural findings. The tumor was located on the pericardium, but autopsy revealed that it had spread extensively in the mediastinum and the lungs. Microscopically, the tumor cells were epithelial like and contained histochemically demonstrable glycogen and hyaluronic acid. Immunohistochemical studies of the tumor demonstrated positive immunoreactivity for cytokeratin 19, muscle actin HHF35, epithelial membrane antigen, CA125, p53 and p21WAF1/CIP1 whereas the tumor was negative for cytokeratins 10 and 17, carcinoembryonic antigen, vimentin, epithelial antigen BerEP4, S-100, c-erbB2 and bcl-2. A high MIB-1 labeling index was noted. Under the electron microscope the tumor cells exhibited long, thin villi. The operation and autopsy findings thus revealed this to be a very rare case of malignant pericardial mesothelioma in a young man.