Malignant Pleural Mesothelioma  

Malignant pleural mesothelioma is the most common type of mesothelioma. It develops in the cells of the pleura, a serous membrane located between the lungs inside and the chest wall outside. Although smoking increases the risk of lung tumors, it does not affect the risk of developing mesothelioma. The tumor is due, in 80% of cases, to inhalation of asbestos microfibers. Once inhaled, these microscopic fibers become lodged deep in the respiratory tree to the alveoli and migrate to the pleura. Mesothelioma may take several decades after exposure to asbestos before developing. The disease occurs more often in men, usually men aged between 50 and 70 years.  

Workers at high risk for asbestos are shipbuilders, pipefitters, insulation installers, tile workers, welders, refinery workers, and sanders. The main location of malignant mesothelioma is the pleura, but in rare cases the tumor can be localized to the peritoneum (see peritoneal mesothelioma) or the pericardium (see pericardial mesothelioma).   

The signs of mesothelioma are often delayed and are not explicitly related to the disease: Chest pain, nerve pain (neuralgia) in the arm, back pain in the scapula (see mesothelioma symptoms for more details). In severe cases, the tumor may lead to development of pleural effusion (fluid often bloody between the layers of the pleura) associated with breathlessness (dyspnea). 

In contrast to other lung tumors, lung X-ray is rarely helpful in the diagnosis of malignant pleural mesothelioma except at an advanced stage. CT scan and MRI are the most useful tests in the detection of the disease; the diagnosis will be confirmed by a biopsy of the pleura. Microscopic examination of the fluid in case of effusion can reveal presence of malignant cells.  

There is no cure for pleural mesothelioma. At an early stage, surgery can give results more or less satisfying; radiation therapy can slow the progression of the tumor; chemotherapy can be used as a palliative treatment to reduce symptoms. In most cases, the prognosis of pleural mesothelioma is bad.