Malignant mesothelioma is a cancer that starts in cells in the linings of certain parts of the body, especially the chest or abdomen.
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 mesothelium. The mesothelium helps protect your organs by making a special lubricating fluid that allows organs to move around. For example, this fluid makes it easier for the lungs to move inside the chest during breathing. The mesothelium has different names in different
parts of the body:
parts of the body:
· In the chest it is called the pleura.
· In the abdomen it is called the peritoneum.
· In the space around the heart it is called the pericardium.
· In the abdomen it is called the peritoneum.
· In the space around the heart it is called the pericardium.
Tumors of the mesothelium can be non-cancerous (benign) or cancerous (malignant).
Malignant mesothelioma
A cancerous tumor of the mesothelium is called a malignant mesothelioma, although this is often simply shortened to just mesothelioma. Mesotheliomas can start in 4 main areas in the body.
· Pleural mesotheliomas start in the chest cavity. They account for about 3 out of 4 mesotheliomas.
· Peritoneal mesotheliomas begin in the abdomen. They make most of the remaining cases.
· Pericardial mesotheliomas start in the cavity around the heart and are very rare.
· Mesotheliomas of the tunica vaginalis are very rare tumors that start in the covering layer of the testicles, which is actually an outpouching of peritoneum into the scrotum.
Malignant mesotheliomas can also be classified into 4 types based on how the cells are arranged when looked at under a microscope:
· Epithelioid: About 50% to 60% of mesotheliomas are of this type. It tends to have a better outlook (prognosis) than the other types.
· Sarcomatoid (fibrous): About 10% to 20% of mesotheliomas are of this type.
· Mixed (biphasic): These mesotheliomas have both epithelioid and
· Sarcomatoid (fibrous): About 10% to 20% of mesotheliomas are of this type.
· Mixed (biphasic): These mesotheliomas have both epithelioid and
sarcomatoid areas. They make up about 30% to 40% of mesotheliomas.
· Desmoplastic: These are rare.
· Desmoplastic: These are rare.
