Sarcomatous, epithelial, and mixed are the three major types of mesothelioma. Pleural mesothelioma usually begins at the lower part of the chest as discrete plaques and nodules that come together and produce a sheetlike neoplasm. The tumor may invade the diaphragm and encase the surface of the lung and interlobar fissures. From there, the pleural lymphatics carry it to the pleural surface. Signs and symptoms result from pleural effusion, restricted lung function, tumor mass, infection, and advanced disease. The tumor may also grow along drainage and thoracotomy tracts. As the disease progresses, it often extends into the chest wall and mediastinum and may extend into the esophagus, ribs, vertebra, brachial plexus, and superior vena cava. Most malignant mesotheliomas have complex karyotypes, with rearrangement of many chromosomes. A loss of a single copy on chromosome 22 is the most common abnormality.

The link between mesotheliomas and asbestos exposure is well established. The shipbuilding, construction, ceramics, paper milling, auto parts, railroad, and insulation industries are all associated with asbestos exposure. Smoking alone doesn’t increase the risk for developing a mesothelioma; however, coupled with asbestos exposure, smoking increases the risk by about 50%. Mesotheliomas rarely result from chronic inflammation, radiation, or recurrent lung infection.

Mesotheliomas have a latency period of 20 to 45 years from exposure to tumor discovery. They typically occur in people older than 50 years and are invariably fatal. With trimodality treatment, median survival is 11 months, with some patients surviving 16 to 19 months and a few as long as 5 years. Without treatment, mesothelioma is fatal in 4 to 8 months.