Malignant mesothelioma is a rare type of cancer that occurs in the thin layer of cells lining the body's internal organs, known as the mesothelium. There are three recognized types of mesothelioma. Pleural mesothelioma is the most common form of the disease, accounting for roughly 70% of cases, and occurs in the lining of the lung known as the pleura. Peritoneal mesothelioma occurs in the lining of the abdominal cavity, known as the peritoneum and pericardial mesothelioma originates in the pericardium, which lines the heart.
The principal function of the lungs is the exchange of gases between the air we breathe and the blood. Through the lung, carbon dioxide is removed from the bloodstream and oxygen from inspired air enters the bloodstream. The right lung has three lobes, while the left lung is divided into two lobes and a small structure called the lingula that is the equivalent of the middle lobe. The major airways entering the lungs are the bronchi, which arise from the trachea. The bronchi branch into progressively smaller airways called bronchioles that end in tiny sacs known as alveoli where gas exchange occurs. The lungs and chest wall are covered with a thin layer of tissue called the pleura.
Lung cancers can arise in any part of the lung, but 90%-95% of cancers of the lung are thought to arise from the epithelial, or lining cells of the larger and smaller airways (bronchi and bronchioles); for this reason, lung cancers are sometimes called bronchogenic carcinomas or bronchogenic cancers. Cancers can also arise from the pleura (the thin layer of tissue that surrounds the lungs), called mesotheliomas, or rarely from supporting tissues within the lungs, for example, blood vessels.
Asbestos exposure is the single known cause of mesothelioma. Inhaled or ingested asbestos fibers may cause an inflammation of internal tissue and disrupt organ function which leads to the development of the disease. Asbestos products were used extensively throughout the 20th century in a wide variety of applications. Many of these products were responsible for asbestos exposure sustained by both the individuals who manufactured the products as well as those who used them at commercial and industrial jobsites including shipyards, refineries, power plants, steel plants and more. Several asbestos companies continued to produce these products even after they were known to be hazardous and harmful to workers and their families. Those who have become sick because of exposure to these products may now be eligible for financial compensation if they were wrongfully exposed.