Define Mesothelioma
Mesothelioma is an asbestos related cancer of the lining of various organs in the body. In mesothelioma, malignant cells develop in the mesothelium which is the protective lining that covers the internal organs. The mesothelium develops from the mesoderm in the embryo which lines the embryonic body cavity. The mesoderm ultimately forms the layer of cells that become the visceral lining of the organs or the parietal sac around a cavity. The most common sites are the lining of the lung (pleura), the abdomen (peritoneum) or the heart (pericardium). There are three subtypes of mesothelioma which correspond to the types of cells seen in each site. These subtypes are epithelioid, sarcomatoid and biphasic or mixed. Each subtype has a specific microscopic appearance to allow this determination. The subtypes differ in their response to treatment and the aggressiveness of their disease.
