Mesothelioma is a kind of cancer that is nearly always caused by being exposed to asbestos. In this disease, malignant cells develop in the mesothelium, a protecting lining that covers most of the body’s internal organs. Its most common site is the pleura ( outer lining of the lungs and internal chest wall ), but it could also occur in the peritoneum ( the liner of the intestinal cavity ), the heart, the pericardium ( a sac that surrounds the heart ) or tunica vaginalis. . . . → Read More: Mesothelioma Survival Is Possible