Malignant mesothelioma is a rare cancer that develops in the mesothelium, a membrane that covers and protects the lungs (pleura), the abdominal cavity (peritoneum) and heart (pericardium). Under normal conditions, the mesothelial cells multiply and then die to be replaced by other healthy cells. Malignant mesothelioma occurs when normal cells of the mesothelium lose control and spread rapidly and abnormally.
Depending on the group of cells affected, malignant mesothelioma can be: malignant pleural mesothelioma, malignant peritoneal mesothelioma or malignant pericardial mesothelioma.
Peritoneal mesothelioma: peritoneal mesothelioma is a type of cancer that develops in the lining of the abdomen; it is the second most common of mesotheliomas, representing about one fifth of all the disease. Usually, peritoneal mesothelioma is characterized by a slow malignant development of a group of ‘mesothelial’ cells on the peritoneum, a serous membrane formed by a single layer of epithelial cells lining the abdomen and viscera. The detection of peritoneal mesothelioma is done by X-ray and CT scan, and confirmed by biopsy.
Pleural Mesothelioma: p leural 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.
Pericardial mesothelioma: Pericardial mesothelioma develops in the pericardium, a double-walled sac that contains the heart and the roots of large blood vessels. The onset of the disease is caused by inhalation of asbestos. You can be exposed to asbestos due to your occupation or, secondarily, through contact with workers or family members exposed to asbestos. The pathogenic effects of asbestos are slow; mesothelioma can wait until 20 to 50 years or more after exposure before manifesting.