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Mesothelioma (or, more precisely, malignant mesothelioma) is a rare form of cancer that develops from cells of the mesothelium, the protective lining that covers many of the internal organs of the body. Mesothelioma is most commonly caused by exposure to asbestos. The most common anatomical site for mesothelioma is the pleura (the outer lining of the lungs and internal chest wall), but it can also arise in the peritoneum (the lining of the abdominal cavity), the pericardium (the sac that surrounds the heart), or the tunica vaginalis (a sac that surrounds the testis).〔 Most people who develop mesothelioma have worked in careers such as mining, where they inhaled or ingested asbestos fibers, or were exposed to airborne asbestos dust and fibers in other ways. Washing the clothing of a family member who worked with asbestos also creates a risk for developing mesothelioma. Signs and symptoms of mesothelioma include shortness of breath due to pleural effusion (fluid between the lung and the chest wall), chest wall pain and constitutional signs such as unexplained weight loss. The diagnosis may be suspected based on chest X-ray and CT scan findings, but must be confirmed either by examining serous effusion cytology or with a biopsy (removing a sample of the suspicious tissue). A thoracoscopy (inserting a tube with a camera into the chest) can be used to acquire biopsy material, and allows the introduction of substances such as talc to obliterate the pleural space (a procedure called pleurodesis), preventing more fluid from accumulating and pressing on the lung. Despite treatment with chemotherapy, radiation therapy or sometimes surgery, mesothelioma carries a poor prognosis. Research about screening tests for the early detection of mesothelioma is ongoing. ==Signs and symptoms== Symptoms or signs of mesothelioma may not appear until 20 to 50 years (or more) after exposure to asbestos. Shortness of breath, cough, and pain in the chest due to an accumulation of fluid in the pleural space (pleural effusion) are often symptoms of pleural mesothelioma. The most common symptoms of peritoneal mesothelioma are abdominal swelling and pain due to ascites (a buildup of fluid in the abdominal cavity). Other features may include weight loss, fever, night sweats, poor appetite, vomiting, constipation, and umbilical hernia. If the cancer has spread beyond the mesothelium to other parts of the body, symptoms may include pain, trouble swallowing, or swelling of the neck or face. These symptoms may be caused by mesothelioma or by other, less serious conditions. Mesothelioma that affects the pleura can cause these signs and symptoms:〔 * Chest wall pain * Pleural effusion, or fluid surrounding the lung * Shortness of breath * Fatigue or anemia * Wheezing, hoarseness, or cough * Blood in the sputum (fluid) coughed up (hemoptysis) In severe cases, the person may have many tumor masses. The individual may develop a pneumothorax, or collapse of the lung. The disease may metastasize, or spread to other parts of the body. Tumors that affect the abdominal cavity often do not cause symptoms until they are at a late stage. Symptoms include: * Abdominal pain * Ascites, or an abnormal buildup of fluid in the abdomen * A mass in the abdomen * Problems with bowel function * Weight loss In severe cases of the disease, the following signs and symptoms may be present: * Blood clots in the veins, which may cause thrombophlebitis * Disseminated intravascular coagulation, a disorder causing severe bleeding in many body organs * Jaundice, or yellowing of the eyes and skin * Low blood sugar level * Pleural effusion * Pulmonary emboli, or blood clots in the arteries of the lungs * Severe ascites A mesothelioma does not usually spread to the bone, brain, or adrenal glands. Pleural tumors are usually found only on one side of the lungs. Pericardial mesothelioma is not well characterized, but observed cases have included cardiac symptoms, specifically constrictive pericarditis, heart failure, pulmonary embolism, and cardiac tamponade. They have also included nonspecific symptoms, including substernal chest pain, orthopnea (shortness of breath when lying flat), and cough. These symptoms are caused by the tumor encasing or infiltrating the heart.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mesothelioma」の詳細全文を読む スポンサード リンク
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