Mesothelioma is cancer that affects the mesothelial cells. The most common form of mesothelioma affects the lining of the lung. Two to three thousand cases of mesothelioma are diagnosed annually.
Malignant mesothelioma affects the membranes of certain large body cavities. These cavities, called the serous cavities, house certain organs in the body. The membranes that surround these cavities are the serous membranes; they serve to protect these major organs as the organs move against each other during typical daily body functioning. The serous membranes derive from specialized cells called mesothelial cells, which create the mesothelium. Cancer that occurs in the mesothelium tissue is mesothelioma.
Mesothelioma is most common in the lining surrounding the lung, but it also develops in the perdicardium, in the peritoneum and in the tunica vaginalis testis.
All mesotheliomas are malignant. They start as a local tumor and spread to include most of the surrounding tissues and organs. Originally, fibrous cists and other non-cancerous growths appearing in the serous membranes were thought to be mesotheliomas, and were termed 'benign fibrous mesothelioma" and "multicystic mesothelioma." They are now known not to originate in the mesothelial cells. These conditions are typically localized, non-cancerous and do not spread rapidly.
Most malignant mesotheliomas are associated with previous exposure to fibrous minerals such as asbestos. There is indisputable evidence of the fibers' role in the development of mesothelioma.
Although mesothelioma is rare, it is a deadly disease. It is often in the advanced stages when it is detected, so the outlook for the patients is not as good as it is for the cancers that are detected earlier.
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