A layer of specialized cells called mesothelial cells lines the inside of the chest, the abdomen, and the space around your heart. These cells also cover the outer surface of most of your internal organs. The lining formed by these cells is called the mesothelium
The mesothelium helps protect your organs by making a special lubricating fluid that allows organs to move. For example, this fluid makes it easier for your lungs to move (expand and contract) inside the chest when you breathe. The mesothelium has different names in different parts of the body:
- The pleura coats the lungs and the cavity containing the lungs in the chest.
- The peritoneum coats the abdominal cavity and many of the organs within that cavity.
- The tunica vaginalis coats the testicles.
- The pericardium coats the heart and creates the cavity that holds the heart in the chest.
Mesothelial tumors can be non-cancerous (benign) or cancerous (malignant).