The most common anatomical site for the development of mesothelioma is the pleura (the outer lining of the lungs and internal chest wall), but it can also arise in the peritoneum (the lining of the abdominal cavity), and the pericardium (the sac that surrounds the heart), or the tunica vaginalis (a sac that surrounds the testis).
 Left sided mesothelioma with mediastinal node enlargement : CT scan. Source: wikipedia |  Source: medlineplus |
The tissue that lines your lungs, stomach, heart and other organs is called mesothelium. Mesothelioma is cancer of that tissue. It is a rare but serious type of cancer. It usually starts in the lungs, but can also start in the abdomen or other organs. Most people who develop mesothelioma have worked on jobs where they inhaled asbestos particles. It can take a long time - 30 to 50 years - between being around asbestos and getting the disease. Treatment includes surgery, radiation, chemotherapy or all three.
NIH: National Cancer Institute
