. . . . "Mesothelioma derives directly from the mesothelial cells and does not migrate into the mesothelium from other organs.The most common metastatic tumors that grow in the pleura derive from, in descending order: * breast * lung * ovary * stomach * large intestine * pancreas * thyroid * kidneyFor the pericardial tumors from metastases, the most common originating organs are lung, breast and thyroid." .