Mesothelioma is cancer of the mesothelium, a protective membrane that lines many of the body's internal organs. Most often, mesothelioma occurs in the lining of the lungs, called the pleura.
Mesothelioma is most often diagnosed after a patient sees a doctor because of symptoms such as pain in the lower back, shortness of breath, fatigue, weight loss, abdominal pain and/or swelling. But symptoms alone will not tell your doctor if you have mesothelioma. A medical history, physical exam, and diagnostic tests are necessary to confirm a mesothelioma diagnosis.
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Because mesothelioma is uncommon, it is often misdiagnosed initially. If you have symptoms that suggest you might have mesothelioma, your doctor will likely take a complete medical history to check for symptoms and possible risk factors, especially asbestos exposure. Exposure to asbestos is the No. 1 risk factor for mesothelioma.
Your doctor will also ask about your general health and perform an exam to check for possible signs of mesothelioma. These may include fluid in the chest cavity, abdomen, or pericardium (the thin membrane around the heart).
Depending on the findings of the exam, your doctor may refer you for mesothelioma testing.
There are several different types of mesothelioma tests. These include:
Blood Tests. Blood levels of two substances, osteopontin and soluble mesothelin-related peptides (SMRPs), are often elevated in people with mesothelioma. Although these blood tests cannot confirm a diagnosis of mesothelioma, high levels of these substances make mesothelioma more likely.
Fluid and Tissue Sample Tests. If you have a buildup of fluid in the body that may be related to mesothelioma, your doctor can remove a sample of the fluid by inserting a needle through the skin into the area of fluid buildup. The fluid can then be examined under a microscope for cancer cells. If cancer cells are found, further tests can determine if the cancer is mesothelioma.
This test goes by different names, depending on where the fluid is:
Thoracentesis -- chest cavity
Paracentesis -- abdomen
Pericardiocentesis -- membrane around the heart
Even if your doctor does not find mesothelioma cells in fluid, that doesn't necessarily mean you don't have mesothelioma. Sometimes samples of actual tissue (biopsies) are needed to diagnose mesothelioma.
Biopsies. There are methods of removing tissue to be examined for mesothelioma. They include:
Needle Biopsy. This procedure involves inserting a long, hollow needle through the skin to remove a tiny piece of a tumor. Your doctor may use imaging tests to guide the needle into the tumor. In some cases, the sample may be too small to make a diagnosis and a more invasive procedure is needed.
Thoracoscopy, Laparoscopy, and Mediastinoscopy. In these procedures, the doctor inserts a thin, lighted scope through a small incision in the skin to see potential areas of mesothelioma. Small tools, inserted through additional incisions, can be used to remove pieces of tissue to examine under a microscope. The specific procedure depends on the area being examined.
Thoracoscopy examines the space between the lungs and chest wall
Laparoscopy examines the inside of the abdomen
Mediastinoscopy examines the center of the chest, around the heart