What is Mesothelioma?

Definition:

Mesothelioma is a rare form of cancer in which malignant (cancerous) cells are found in the mesothelium, originating from the cells which form the membrane lining the abdominal cavity (peritoneal membrane or peritoneum) which houses the intestines, or the chest (pleural membrane or pleura) cavity housing the heart and lungs, in which the cells making up those tissues begin to grow out of control. They can invade and damage nearby tissues and organs. Cancer cells can also metastasize (spread) from their original site to other parts of the body.

Beginning first as a flat white plaque, mesothelioma is a tumor that continues to grow around the lungs (pleurae), but may also originate around the abdominal cavity. As mesothelioma progresses, it enters the lungs and invades nearby ribs.

Description:

The mesothelium is a membrane that covers and protects most of the internal organs of the body. It is composed of two layers of cells: One layer immediately surrounds the organ; the other forms a sac around it. The mesothelium produces a lubricating fluid that is released between these layers, allowing moving organs (such as the beating heart and the expanding and contracting lungs) to glide easily against adjacent structures.

The mesothelium has different names, depending on its location in the body. The peritoneum is the mesothelial tissue that covers most of the organs in the abdominal cavity. The pleura is the membrane that surrounds the lungs and lines the wall of the chest cavity. The pericardium covers and protects the heart. The mesothelial tissue surrounding the male internal reproductive organs is called the tunica vaginalis testis. The tunica serosa uteri covers the internal reproductive organs in women.