Diagnosing Mesothelioma

Mesothelioma is diagnosed through a careful assessment of clinical and radiological findings. A tissue biopsy is taken to confirm the diagnosis.

There are several steps in the diagnostic process at the International Mesothelioma Program (IMP):

1. The first step is reviewing the patient’s medical history, including any history of asbestos exposure. We also perform a complete physical exam, including a pulmonary function test (this test can help diagnose lung diseases and measure the severity of the lung problem).
2. Several imaging studies may be performed to identify mesothelioma and determine how far it may have spread.
• A chest X-ray can show any thickening of the pleura (the sac that covers the lungs and lines the chest wall) or calcium deposits on the pleura. An X-ray also can show whether there is an accumulation of fluid around the lungs (called pleural effusion) or in the abdomen (often referred to as ascites).
• A CT (computed tomography) scan helps define the extent of the tumor. The CT scan is an X-ray procedure in which a scanner rotates around the body to produce detailed, cross-sectional images. A CT scan helps determine the location, size, and extent of mesothelioma tumors and can help determine whether the tumor has spread.
• An MRI (magnetic resonance imaging) uses radio waves and strong magnets instead of X-rays. It produces cross sectional slices of the body like a CT scanner, but it also can produce slices that are parallel with the length of your body (both front to back and side to side).
• An echocardiogram uses ultra-high-frequency sound waves to create an image of the heart muscle. An “echo” test can provide useful information, including the size and shape of the heart, its pumping strength, and the location and extent of any damage or heart disease.
3. If the results of these tests indicate the presence of mesothelioma, a biopsy will be taken to confirm the diagnosis. A biopsy is a procedure for obtaining tissue from the body for examination under a microscope by the pathologist.

   A VATS (video-assisted thoracic surgery) pleural biopsy involves making one or two small incisions in the chest to insert a small video camera and instruments with which to take the sample. The surgeon watches a TV monitor connected to the camera to enable precision in taking the sample. If the sample is taken from the abdomen, it is called a peritoneal biopsy. Both are performed using general anesthesia, so the patient is asleep.

   Although a biopsy is the most effective procedure for diagnosis, mesothelioma cells can look like other types of cancer. So a pathologist will perform special lab tests on the tumor tissue removed during biopsy and if necessary, will use an electron microscope to confirm the diagnosis.

4. Doctors study the lymph nodes to see whether a mesothelioma tumor has spread. There are many clusters of lymph nodes throughout the body. The lymph nodes in the center of the chest (the mediastinum) are called mediastinal nodes. So a mediastinoscopy is performed to check them. This involves inserting a lighted tube under the chest bone and moving it down into the chest so the surgeon can see the lymph nodes and take samples that will be checked for the presence of tumor cells. This procedure is performed under general anesthesia.
5. Occasionally, diagnosis is made by removing fluid (pleural effusion) from the chest with a needle and then having the pathologist study the cells in the fluid. The sensitivity of this approach is unfortunately less than 50 percent.

Some steps in the process of diagnosing mesothelioma

• Complete medical history
• Comprehensive physical exam
• Lung function test
• Imaging studies
• Biopsy
• Lymph node study