Mesothelioma is a form of cancer characterized by the growth of tumors on the mesothelium, a tissue that lines the body’s organs. Mesothelioma can be classified in two ways, either by the region of the body that it affects, or by the type of cells that make up the tumor. Mesothelioma usually affects one of three different areas of the body, the chest (pleural mesothelioma), the abdomen (peritoneal mesothelioma), or the heart (pericardial mesothelioma). As for cell types, doctors will classify the cells as either epithelioid, sarcomatoid, or biphasic.
Pleural mesothelioma affects the membrane that surrounds and protects a person’s lungs and chest cavity. This type of mesothelioma is the most common, and represents approximately three out of every four cases of the disease. It occurs when a person breathes in asbestos fibers, which lodge in their lungs, and cause irritation and scarring. This irritation, known as asbestosis, can eventually lead to the development of tumors. However, this whole process can take 20 to 50 years after the person’s first asbestos exposure. Common symptoms of this type of mesothelioma include persistent cough, difficulty swallowing, shortness of breath, chest pain, fatigue, and coughing up blood.
Peritoneal mesothelioma affects the tissue that lines someone’s abdominal organs like their liver or stomach. Unlike pleural mesothelioma, which occurs when a person inhales asbestos, peritoneal mesothelioma is caused by a person’s swallowing the fibers. Once again, these fibers can lodge in the peritoneum and lead to scarring, irritation, and, possibly, tumors. This form of the cancer is rarer and only accounts for approximately 10 to 20 percent of the total number of mesothelioma cases. The symptoms of peritoneal mesothelioma include abdominal pain, swelling, nausea, diarrhea, constipation, nausea, and fatigue. This form of the cancer can also take up to 50 years to develop, making it difficult to properly diagnose.
Pericardial mesothelioma is considerably rarer than the other two forms of the disease, making up only 1 to 6 percent of the total number of mesothelioma cases. This type of mesothelioma affects the tissue that surrounds a person’s heart known as the pericardium. Doctors believe that asbestos causes this form of mesothelioma when it enters a person’s bloodstream and makes its way to the pericardium. This form of the cancer is particularly deadly, with a 50 percent survival rate of just six months. Common symptoms of this type of mesothelioma can include irregular heartbeat, cough, chest pain, heart murmurs, and chest pain.
Doctors also classify mesothelioma based on its histologic cell type, which means the specific makeup of the tumor’s cells. The most common cell type for mesothelioma is epithelioid, which accounts for 50 to 70 percent of all mesothelioma cases. Cells in this type appear generally healthy and may be the most easily treated of the histologic types. Another, rarer, histologic type is sarcomatoid mesothelioma, which involves long, spindle-shaped cells. This form of the cancer is much more aggressive than epithelioid mesothelioma. The final type of the cancer is biphasic mesothelioma, which occurs when the tumor has both epithelioid and sarcomatoid cells in it at the same time.