Mesothelioma is the growth of malignant cells in mesothelium, the thin membrane covering the body's internal organs. This mesothelium lining covers the pleural, peritoneal and pericardial cavities. Pleura is a membrane covering the lungs and it is the most common location where mesothelioma cancer occurs also known as pleural mesothelioma. Peritoneum, the protective covering that lines the abdominal cavity may also develop malignant tumors and cause peritoneal mesothelioma.
Mesothelioma is one of the rarest cancers in the world that is caused only by exposure to asbestos. Its exposure can be direct, by inhalation of asbestos or indirect exposure in which the asbestos particles are inhaled from the clothing, hair, equipment or other articles that were previously exposed to asbestos.
Causes of Mesothelioma
Asbestos is a naturally occurring fibrous mineral that is mined in different parts of the world due to its wide utility in various industries. However, it is a deadly carcinogen too and a mojor cause of mesothelioma and asbestosis.
Asbestos fibers are known to cause cancer of the mesothelium. Asbestos is the fibrous form of several minerals and hydrous silicates of magnesium found under ground. There are 3 types of asbestos, the blue one, the while one and the brown one. Of all these 3 types, the blue one also called amphibole, long and thin in structure is more carcinogenic than white or chrysolite asbestos or the brown one known as amosite.
However, in some cases the brown asbestos has also been found to cause mesothelioma. And it is for this reason that people exposed to asbestos even for a short period are vulnerable to the disease.
Pleural Mesothelioma
Asbestos fibers are very fine and easily make their way to the lungs where they settle down in the parenchyma of the lung and penetrate the pleura that later develops malignant mesothelial plaques.
Pleura, which anchors lungs to the chest cavity, is itself a double-layered membrane. The inner layer called visceral pleura surrounds the lungs, while the outer one, known as parietal pleura, forms the lining of the pleural or chest cavity. The two pleural layers are filled with a fluid that helps them to slide over each other as we breathe. As the disease progresses, the delicate pleural membranes thicken and press the lungs. A fluid secreted by the malignant cells, pleural effusion, may also collect between visceral and parietal pleurae that causes problem in breathing and other complications.
Peritoneum Mesothelioma
The asbestos fibers may also cause cancer in the peritoneum, known as peritoneal mesothelioma. This leads to thickening of the membranes surrounding abdominal organs and collection of a fluid, ascites in the abdominal cavity making it swell.
Though it is yet not clear how peritoneal mesothelioma develops, it is believed that from lungs, the asbestos fibers are transported to abdomen and its organs by the lymphatic system or they may be deposited in the gut through saliva contaminated by the asbestos fibers.
Pericardial Mesothelioma
This is the rarest type of mesothelioma cancer that comprises of only 5% of all the mesothelioma cases. Like other types of mesothelioma cancer, pericardial mesothelioma is also caused by the inhalation of asbestos dust and fibers. The lining of the chest cavity which protects the heart is known as pericardium. It is provided with a natural fluid or mucous that provide continuous lubrication to the heart so that it can work properly and perform its functions.
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