What Is Mesothelioma?

Mesothelioma is a rare type of tumor that arises in the mesothelium. The mesothelium is a thin membrane that lines the cavities of the body (such as the chest and abdomen) and also covers and protects most of the body's internal organs. In the chest, the mesothelium is known as the pleura, where it covers the lungs (visceral pleura) and lines the internal chest wall (parietal pleura). There is a space between the visceral and parietal pleura that normally contains about 10 mls of lubricating fluid that reduces friction between the chest wall and the lungs. The mesothelium surrounding the heart is called the pericardium and also serves to prevent friction between the heart and the chest wall. In the abdomen, the mesothelium is called the peritoneum which reduces friction between the internal organs of the abdomen and the abdominal wall. Mesothelioma can also occur in the lining of the scrotum and the ovaries.

Mesothelioma can be either benign or malignant. Both types are a tumor that affects the movement of the internal organs and limits their effectiveness. Benign mesothelioma may occur wherever there is mesothelium. It is localized and does not spread to nearby tissues. It may cause problems because of the mass of the tumor that can compress or block adjacent structures. Benign mesothelioma can usually be managed by surgical removal and has no association with asbestos exposure.

Malignant mesothelioma is a cancerous tumor that is closely correlated to asbestos exposure. Most malignant mesothelioma occurs in the pleura (65-70%) but may also arise in the peritoneum (25%), the ovaries and scrotum, or the pericardium.