What is the mesothelium?
Each time you your lungs expand during a breath, their movement within your chest is eased by a smooth membrane called the pleura. Imagining it sort of like a deflated baloon, the pleura is technically one layer but functions as two. The cells of the mebrane produce a fluid between the layers allowing it to slide against itself, easing the movement of the lungs as they expand and contract, pushing against other organs, such as the heart, and the chest cavity.Where it contacts lungs, it is called the visceral pleura, while the layer that covers the body walls is called the parietal pleura, Similar membranes exist around the abdominal cavity, heart, and internal reproductive organs, performing the same function. Collectively, these mebranes are called the mesothelium. Cancer of the mesothelium—a disease in which mesothelial cells abnormally divide out of control—is called malignant mesothelioma.
Mesothelium: Types of Mesothelioma
Cancer may arise in any of the mesothelial membranes. Tumors in this lining are known as mesotheliomas, or mesotheliomatas.
- Pleura: Pleural Mesothelioma
- Covering the lungs and thorasic cavity, most mesotheliomas arise out of the pleura. The space between the visceral and pareital pleural (inner and outer, respectively) is known as the pleural space and normally contains a small amount of the lubricating liquid mesothelial cells present that assists with the movement of the lungs. Malignant pleural mesothelioma is a cancer originating in the pleura. Approximately two-thirds of mesothelioma cases originate in the pleura.
- Peritoneum: Peritoneal Mesothelioma
- After the pleura, the abdominal mesothelium, or peritoneum, is the most likely site for mesotheliomas. Maligant peritoneal mesothelioma is the second-most common type of mesothelioma, although significantly more rare, making only around one-third of diagnosed mesotheliomas. Like the pleura, the peritoneum has an outer and inner layer known as the parietal peritoneum, which is attached to the abdominal wall, and visceral peritoneum that is wrapped around organs within the intraperitoneal cavity. Peritoneal mesothelioma is sometimes called abdominal mesothelioma.
- Pericardium: Pericardial Mesothelioma
- The pericardium surrounds the heart and it is from this mesothelium that malignant pericardial mesothelioma arises. It is much rarer than either pleural or peritoneal mesothelioma.
- Tunica Vaginalis Testis, Tunica Vaginalis Uteri: Mesothelioma of
- Finally, mesotheliomas may arise out of the mesothelium that surrounds the internal reproductive organs. In women, this is known as malignant mesothelioma of the tunica vaginalis uteri and in men, malignant mesothelioma of the tunica vaginalis testis.
What causes mesothelioma?
The only known cause of mesothelioma is exposure to asbestos. The exact changes that the asbestos fibres cause in the mesothelium that results in the development of cancerous cells is unknown.Used as a fire retardant, insulator, and strengthener, asbestos was commonplace in many mills, mines, and other industrial and construction sites. Without proper wetting or suspention in resins, microscopic asbestos fibres are easily made airborne. Without proper protection via respirators and ventilation, asbestos fibres could be easily inhaled and ingested by workers. Left unaware of the risks by asbestos companies, workers' treated the dust as a nuisance more than anything, arriving home coated in asbestos dust, and unknowingly putting their their spouses and children at risk of contracting an asbestos-related disease such as mesothelioma.As mesothelioma diagnoses from secondary exposures such as wives and children reveal, there is no known safe level of asbestos exposure. However, workers who have been exposed to large amounts of asbestos or exposed for a long time are more likely to develop mesothelioma or another asbestos-related disase.
What are the symptoms of mesothelioma?
Malignant pleural mesothelioma can result in hindered expansion of the lungs, causing a feeling of tightness or pain in the chest and shortness of breath (dyspnea). Pain is sometimes an indicator of the tumor invading the chest wall, while breathlessness is usually caused by pleural effusions. Pleural effusions are an excess fluid buildup in the pleural space (between the visceral and parietal pleura). Night sweats and unexplained weight loss may also be experienced.Malignant peritoneal mesothelioma may cause a collection of fluid in the abdomen (ascites) and abdominal pain, Similar to pleural mesothelioma, abdominal pain as a result of peritoneal mesotheliioma is usually caused by solid tumor masses; the excess fluid collection may result in swelling, however, this swelling is usually not painful. Weight loss, fever, anemia, and bowel obstruction are also potential symptoms of peritoneal mesothelioma.
How is mesothelioma diagnosed?
Mesotheliomas are typical found by chest x-ray and/or CT scan. An ultimate diagnosis can only be confirmed by biopsy. The most important thing to remember is to advise your doctors of and asbestos exposure history, even if it is remote.
