Malignant mesotheliomas are very aggressive tumors that arise from the superficial serosal cells that cover the peritoneal, plural, and pericardial cavities. In the pleural cavity inside the chest, the serosal cells cover the outer surface of the lungs and inner surface of the chest wall and diaphragm. Exposure to asbestos fiber is the primary cause of development of malignant mesothelioma. Several studies have shown the close relationship between asbestos exposure and the development of malignant mesothelioma. Recent investigations has given some evidence to suggest that a virus, called simian virus 40 (SV40) is a significant contributing factor in the development of mesotheliomas.
There is a long latent period between the time of exposure to asbestos and the development of mesothelioma. This latency duration for the development of malignant mesothelioma may suggest the presence of complex interaction of various factors including some genetic mutations that would finally culminate in the development of malignant mesothelioma. Several clonal abnormalities could be seen mesothelioma cells, and the presence of these clonal genetic abnormalities in malignant mesotheliomas supports this assumption of a slow evolution of malignant mesothelioma. Mesothelioma cells may show chromosomal aberrations, and these chromosomal aberrations may be in the form of loss of genetic materials which may represent loss of genes that usually suppressor cancer formation (tumor suppressor genes). Loss of these tumor suppressor genes may get rid of the normal control mechanisms of the cell that orderly regulates the complex process of cell division ultimately resulting in malignancy.