What Is Malignant Mesothelioma?

A layer of specialized cells called mesothelial cells lines the chest cavity, abdominal cavity, and the cavity around your heart. These cells also cover the outer surface of most of your internal organs. The tissue formed by these cells is called mesothelium. The mesothelium helps protect your organs by producing a special lubricating fluid that allows organs to move around. This fluid makes it easier for the lungs to move inside the chest during breathing. The mesothelium of the chest is called the pleura and the mesothelium of the abdomen is known as the peritoneum. The mesothelium of the "sac-like" space around the heart (pericardial cavity) is called the pericardium. Tumors of the mesothelium can be non-cancerous (benign) or cancerous (malignant). A malignant tumor of the mesothelium is called a malignant mesothelioma; however, malignant mesothelioma is often simply called mesothelioma.