Malignant mesothelioma is a disease in which a cancerous tumor grows on the mesothelium - the sac lining the internal body cavities. The specific type of mesothelioma is named for the tissue where the cancer started. Pleural mesothelioma starts in the chest, in the pleura that surrounds the lungs (outer lining of the lungs and internal chest wall). It makes up about 70% of mesothelioma cases. Peritoneal mesothelioma starts in the lining of the abdominal cavity.
Although sometimes referred to as "asbestos lung cancer", mesothelioma is not the same as lung cancer. Lung cancers occur inside the lung itself; mesothelioma occurs in the lining of the lung. Mesothelioma is rare, striking fewer than 3000 Americans per year.
[mesotheliomaweb.org]