Mesothelioma Lung Cancer Definition

Mesothelioma is an uncommon form of cancer that attacks the protective lining around the lungs (pleura), abdominal organs (peritoneum), or heart (pericardium). Most cases of mesothelioma begin in the pleura or peritoneum.

Mesothelioma is most frequently caused by exposure to asbestos. Asbestos is a group of naturally occurring minerals. Asbestos releases strong, microscopic fibers that may injure the protective linings surrounding the body’s organs. In the past, asbestos was widely used in many industrial products including insulation because of its high resistance to heat and fire.

Mesothelioma is a rare form of cancer that arises in the mesothelium. The mesothelium is made up of visceral and parietal membranes (thin layers of tissue), which surround organs and body cavities, such as the lungs or abdomen. The visceral membrane immediately surrounds the organ, and the parietal membrane is a sac covering the visceral membrane. There is a lubricating fluid between these membranes that make up the mesothelium.

This fluid helps organs move easily among surrounding structures. In the case of the lung, it helps reduce friction between the lung and chest wall during normal breathing as the lung expands. There are different types of mesothelioma, depending where it is found in the body. In the abdomen, it is called peritoneal mesothelioma; on the lungs, it is called pleural mesothelioma; and if it develops on the heart, pericardial mesothelioma.