Malignant mesothelioma of the pericardium: case reports and immunohistochemical studies including Ki-67 expression.

Pericardial malignant mesothelioma (PMM) is extremely rare compared with pleural cases of mesothelioma. We present the clinical and pathological features of three autopsy cases with PMM. All three cases showed rapid progress and died of heart failure. Detailed examination was obtained from the autopsy. Macroscopic appearances of each case showed a thickened pericardium due to tumor invasion. Microscopic observations of all cases led to a diagnosis of epithelial-type malignant mesothelioma (MM). The results of immunohistochemical examinations were similar to the previous published work on pleural mesothelioma. To disclose the pathological characteristics of PMM, we analyzed Ki-67 labeling index (LI) of three cases of PMM and five cases of pleural MM that died within 2 years. The difference of Ki-67 LI between PMM and pleural MM was not significant (P > 0.05). The poor prognosis of patients with PMM must be caused by restricted cardiac wall motion due to tumor involvement, in addition to the tumor proliferation itself.