Types of mesothelioma are classified according to the location of the mesothelium that is affected. Mesothelium is a protective membrane that covers most internal organs of the body. Internal organs include the abdominal cavity, lungs, chest cavity, heart and reproductive organs. The membrane that surrounds organs in the abdominal cavity is called the peritoneum. The membrane that surrounds the lungs and lines the walls of the chest cavity is called the pleura. The membrane that surrounds the heart is called the pericardium. The membrane that surrounds male internal reproductive organs is called the tunica vaginalis testis and tunica serosa uteri is the membrane that surrounds female internal reproductive organs. Mesothelioma is a cancer of the mesothelium membrane. The type of mesothelioma that a person may develop is based on the particular mesothelium membrane that is affected.

A lubricating fluid is naturally contained within the mesothelium membrane to protect the organ that it surrounds and also to allow the organs to glide easily against other structures within the body. As mesothelioma progresses fluid builds up in the mesothelium membrane. When fluids build up in the pleural membrane that surrounds the lungs and chest cavity or fluid builds up in the pericardium membrane that surrounds the heart, it is called effusion. When fluids build up in the peritoneal membrane that surrounds the abdominal cavity, it is called ascites. Effusion and ascites are acute symptoms that characterize a late stage and malignant form of mesothelioma.

The most common types of mesothelioma are peritoneal mesothelioma, which is cancer of the lining of the abdominal cavity and pleural mesothelioma, which is cancer of the lining of the membrane that covers the lungs and lines the walls of the chest cavity. Pericardial Mesothelioma, which is cancer of the lining of the heart, and the cancers of the reproductive organs, vaginalis testis mesothelioma and serosa uteri mesothelioma, are rare forms of mesothelioma.

The study of mesothelioma is an evolving science and an exact cause of the disease has not been defined. Mesothelioma is characterized by risk factors that are common to patients with the disease rather than causes. While much research and many studies have examined pleural and peritoneal mesothelioma, very little is known about the other forms of the cancer.

The primary risk factor for mesothelioma is exposure to asbestos. The government and medical community have been aware of the high risk factors of asbestos exposure to human health for many years. The relation between asbestos, cancer, lung disease and respiratory problems has been acknowledged and studied. However, the discovery of mesothelioma and the acceptance of the disease as its own distinct form of cancer are relatively new concepts in medical science. In the past, instances of mesothelioma were misdiagnosed and confused with other illnesses and diseases since the symptoms of mesothelioma are not distinct and are characteristic of other illnesses and disease. It wasn’t until the late 1990s that mesothelioma was recognized and studied as a separate and distinct form of cancer.

The treatment for mesothelioma varies according to the type and location of mesothelioma. It is important for doctors to determine how far the cancer has progressed once it is diagnosed. X-rays, CAT scans, MRI scans and PET (positron emission tomography) are used to stage mesothelioma. Treatment and outlook will ultimately be determined based on the stage of the disease. However, since pleural mesothelioma is the most studied form of mesothelioma, it is currently the only form of the disease for which a staging system has been developed. As research and development evolve regarding mesothelioma, staging systems are expected to be devised for the other forms of mesothelioma. In the meantime, a generalized system of staging is used for other forms of mesothelioma.