Mesothelioma Diagnosis

Diagnosing mesothelioma is often difficult because the symptoms are similar to those of a number of other conditions. Mesothelioma is diagnosed through a careful assessment of clinical and radiological findings proceeded by a confirming tissue biopsy.

Diagnosis begins with a review of the patient's medical history, including any history of asbestos exposure. A complete physical examination will be performed along with a lung function test. Lung function tests can help diagnose lung diseases and measure the severity of the lung problem.

Radiological studies, including chest X-ray, Computed Tomography or CT (CAT) scan and Magnetic Resonance Imaging (MRI), play a major role in the evaluation of the patient with mesothelioma. They are crucial in diagnosing mesothelioma and determining how far the cancer has spread.

A Chest X-ray can show any thickening of the pleura, calcium deposits on the pleura, and whether there is an accumulation of fluid around the lungs (pleural effusion) or in the abdomen (ascites).

A CT scan aids in defining the exact anatomical extent of the tumor. The CT scan is an X-ray procedure that produces detailed cross-sectional images of your body. Instead of taking one picture, like a conventional x-ray, a CT scanner takes many pictures as it rotates around you. A computer then combines these pictures into an image of a slice of your body. The machine will take pictures of multiple slices of the part of your body that is being studied. A CT scan helps determine the location, size and extent of mesothelioma tumors and can help determine whether the tumor has invaded any of the adjacent structures.

A MRI is generally superior to CT in evaluating invasion through the diaphragm (the thin muscle at the bottom of the lung cage that is responsible for breathing) or mediastinum (the area in the chest behind the breast bone and in between the two lungs where the heart, major blood vessels, lymph glands, and nerve tissue exist). MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed and then released in a pattern formed by the type of tissue and by certain diseases. A computer translates the pattern of radio waves given off by the tissues into a very detailed image of parts of the body. Not only does this produce cross sectional slices of the body like a CT scanner, it can also produce slices that are parallel with the length of your body.

An Echocardiogram is a noninvasive (doesn’t involve breaking the skin or entering the body), diagnostic test that uses ultra-high-frequency sound waves - sound waves that are too high in frequency to be heard by the human ear - to create an image of the heart muscle to rule out any heart disease. It can provide a wealth of helpful information, including the size and shape of the heart, its pumping strength, and the location and extent of any damage to its tissues. Echocardiography also is helpful in ruling out pericardial invasion.

All of the steps described above are only preliminary indications of mesothelioma. If the results of these tests indicate the presence of mesothelioma, a biopsy will be taken to confirm this 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 is done under general anesthesia. The procedure should involve one or at most two small incisions that are made in the chest to introduce a telescope and other fine instruments. Removal of a sample of the tumor is done while looking at a monitor screen connected to the telescope. It is important to make sure that the incisions are placed in a location on the chest where they can be incised since tumor cells can contaminate any incision. In a peritoneal biopsy, a small incision is made in the abdomen and a laparoscope is inserted into the abdominal cavity to remove a sample of tumor (laparoscopy).

Although a biopsy is the most effective procedure for diagnosing mesothelioma, malignant mesothelioma cells can look like other types of cancer. Therefore, a pathologist will perform special laboratory tests on the tumor tissue removed during biopsy and if necessary, will utilize an electron microscopes to confirm a diagnosis of mesothelioma.

Another way to occasionally make the diagnosis of mesothelioma is by removing fluid from the chest with a needle and then subject the fluid to cytology study by the pathologist. The sensitivity of this approach is unfortunately less than 50%.

A mediastinoscopy is performed to determine if the tumor has spread to the mediastinal nodes (the lymph nodes in the mediastinum ie the center of the chest). The lymph nodes are bean-sized collections of immune system cells that help the body fight infections and cancers. They exist everywhere in the body and filter infection and tumor cells. Each type of tumor tends to filter and grow in specific lymph node locations. The degree of lymph node involvement helps determine how extensive the tumor is (stage). This is an important determination because treatment varies according to the lymph node status. A mediastinoscopy involves inserting a lighted tube (mediastinoscope) under the sternum (chest bone) at the level of the neck and moved down into the chest. The surgeon is then able to view the lymph nodes in this region and take samples to check for malignant mesothelioma. This procedure, like the pleural biopsy is performed under general anesthesia where the patient is completely asleep.