Malignant mesothelioma is a disease in which malignant (cancer) cells form in the lining of the chest or abdomen.

Malignant mesothelioma is a disease in which malignant (cancer) cells are found in the pleura (the thin layer of tissue that lines the chest cavity and covers the lungs) or the peritoneum (the thin layer of tissue that lines the abdomen and covers most of the organs in the abdomen). This summary is about malignant mesothelioma of the pleura.

Anatomy of the respiratory system, showing the trachea and both lungs and their lobes and airways. Lymph nodes and the diaphragm are also shown. Oxygen is inhaled into the lungs and passes through the thin membranes of the alveoli and into the bloodstream (see inset). Being exposed to asbestos can affect the risk of developing malignant mesothelioma.
Anything that increases your chance of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Many people with malignant mesothelioma have worked or lived in places where they inhaled or swallowed asbestos. After being exposed to asbestos, it usually takes a long time for malignant mesothelioma to occur. Other risk factors for malignant mesothelioma include the following: Living with a person who works near asbestos. Being exposed to a certain virus.
Possible signs of malignant mesothelioma include shortness of breath and pain under the rib cage.
Sometimes the cancer causes fluid to collect around the lung or in the abdomen. These symptoms may be caused by the fluid or malignant mesothelioma. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur: Trouble breathing. Pain under the rib cage. Pain or swelling in the abdomen. Lumps in the abdomen. Weight loss for no known reason.
Tests that examine the inside of the chest and abdomen are used to detect (find) and diagnose malignant mesothelioma.
Sometimes it is hard to tell the difference between malignant mesothelioma and lung cancer. The following tests and procedures may be used: Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits, exposure to asbestos, past illnesses and treatments will also be taken. Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.

Lung biopsy. The patient lies on a table that slides through the computed tomography (CT) machine which takes x-ray pictures of the inside of the body. The x-ray pictures help the doctor see where the abnormal tissue is in the lung. A biopsy needle is inserted through the chest wall and into the area of abnormal lung tissue. A small piece of tissue is removed through the needle and checked under the microscope for signs of cancer. Thoracoscopy: An incision (cut) is made between two ribs and a thoracoscope (a thin, tube-like instrument with a light and a lens for viewing) is inserted into the chest. Peritoneoscopy: An incision (cut) is made in the abdominal wall and a peritoneoscope (a thin, tube-like instrument with a light and a lens for viewing) is inserted into the abdomen. Laparotomy: An incision (cut) is made in the wall of the abdomen to check the inside of the abdomen for signs of disease. Thoracotomy: An incision (cut) is made between two ribs to check inside the chest for signs of disease. Bronchoscopy: A procedure to look inside the trachea and large airways in the lung for abnormal areas. A bronchoscope is inserted through the nose or mouth into the trachea and lungs. A bronchoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue samples, which are checked under a microscope for signs of cancer. Enlarge Bronchoscopy. A bronchoscope is inserted through the mouth, trachea, and major bronchi into the lung, to look for abnormal areas. A bronchoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a cutting tool. Tissue samples may be taken to be checked under a microscope for signs of disease.

Bronchoscopy. A bronchoscope is inserted through the mouth, trachea, and major bronchi into the lung, to look for abnormal areas. A bronchoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a cutting tool. Tissue samples may be taken to be checked under a microscope for signs of disease. Cytologic exam: An exam of cells under a microscope (by a pathologist) to check for anything abnormal. For mesothelioma, fluid is taken from around the lungs or from the abdomen. A pathologist checks the cells in the fluid. Certain factors affect prognosis (chance of recovery) and treatment options. The prognosis (chance of recovery) and treatment options depend on the following: The stage of the cancer. The size of the tumor. Whether the tumor can be removed completely by surgery. The amount of fluid in the chest or abdomen. The patient's age and general health, including lung and heart health. The type of mesothelioma cancer cells and how they look under a microscope. Whether the cancer has just been diagnosed or has recurred (come back).