What is Mesothelioma?

Mesothelioma, more precisely malignant mesothelioma, is a rare form of cancer that develops from the protective lining that covers many of the body's internal organs, the mesothelium. It is usually caused by exposure to asbestos.

Its most common site is the pleura (outer lining of the lungs and internal chest wall), but it may also occur in the peritoneum (the lining of the abdominal cavity), the heart,^[ the pericardium (a sac that surrounds the heart) or tunica vaginalis.

Most people who develop mesothelioma have worked on jobs where they inhaled asbestos particles, or they have been exposed to asbestos dust and fiber in other ways. It has also been suggested that washing the clothes of a family member who worked with asbestos can put a person at risk for developing mesothelioma. Unlike lung cancer, there is no association between mesothelioma and smoking, but smoking greatly increases the risk of other asbestos-induced cancers.

Second Definition 

Malignant mesothelioma is a disease in which a cancerous tumor grows on the mesothelium - the sac lining the internal body cavities. The specific type of mesothelioma is named for the tissue where the cancer started. Pleural mesothelioma starts in the chest, in the pleura that surrounds the lungs (outer lining of the lungs and internal chest wall). It makes up about 70% of mesothelioma cases. Peritoneal mesothelioma starts in the lining of the abdominal cavity.

Although sometimes referred to as "asbestos lung cancer", mesothelioma is not the same as lung cancer. Lung cancers occur inside the lung itself; mesothelioma occurs in the lining of the lung. Mesothelioma is rare, striking fewer than 3000 Americans per year and more all over the world.


What happens inside the body?
The cancerous cells clump together in a malignant tumor.  As it grows, the tumor pushes against and into other organs and healthy tissue, causing symptoms.  Because the mesothelium is a flat thin lining, the mesothelioma tumor often takes a diffuse shape.
In its advanced stage the cancer metastasizes through the lymph system and spreads to other parts of the body.  It is still referred to as mesothelioma because it started in the mesothelium.

Major symptoms of pleural mesothelioma include:

• Shortness of breath caused by expanding pleural effusion
• Persistent dry cough
• Chest pain

Major symptoms of peritoneal mesothelioma include:

• Ascites (fluid in the abdomen)
• Swelling or lumps in the abdomen
• Abdominal pain

Some patients experience few of the visible symptoms.  Formal diagnostic procedures are needed to determine if the cancer is present.