What is Pleural Mesothelioma ?

Pleural

Pleural mesothelioma is a rare form of cancer caused by asbestos exposure. Pleural mesothelioma refers to cancer of the outer lining of the lung and chest cavity (called the “pleura”). It is the most common form of mesothelioma and accounts for approximately 70% of all mesothelioma diagnoses.

Symptoms
The most common symptoms of pleural mesothelioma are difficulty in breathing and pain in the lower back or chest, which are typically caused by pleural effusion (see below). Other less common symptoms include weight loss, fever, fatigue, trouble swallowing, night sweats, cough, and a general feeling of not being well. Occasionally, a patient may not have symptoms at diagnosis.
Please keep in mind that these symptoms may be caused by mesothelioma or by other less serious conditions. Only a doctor, or preferably a mesothelioma specialist can make a definitive diagnosis.

Pleural effusion, is an accumulation of fluid between the parietal pleura (the pleura covering the chest wall and diaphragm) and the visceral pleura (the pleura covering the lungs). Both of these pleural membranes are comprised of mesothelial cells which, under normal circumstances, produces fluid that acts as a lubricant between the lung and the chest wall. Normally, any excess fluid is absorbed back into the system via the lymph vessels and blood. However, when too much builds up and cannot be drained, the result is an effusion. Pleural effusion is broken down into two categories, transudates and exudates. A transudate is a clear fluid that builds up not because the pleura itself is diseased, but rather because of an imbalance between fluid production and removal. An exudate, which is often times a cloudy fluid, results from disease of the pleura and is common to mesothelioma. In order to discover whether the fluid of the effusion is transudate or exudate, a fluid sample must be taken and analyzed.

Diagnosis
It can be difficult to diagnose mesothelioma because many of the mesothelioma symptoms are similar to those of a number of other conditions, including lung cancer and other types of cancers.

If mesothelioma is suspected, a doctor will typically do a physical examination and ask the patient for a complete a medical history which will include the possibility of prior exposure to asbestos. At this point, the most effective way to make a positive pleural mesothelioma diagnosis is for a mesothelioma specialist to examine tissue from the lung or tumor via a thoracoscopy, a mediastinoscopy or a bronchoscopy. There are several additional tests that can be used to assist in confirming the diagnosis of pleural mesothelioma, including a chest x-ray, CT scan, MRI scan, PET scan and examining the pleural fluid.

Thoracoscopy
In this procedure, a small incision is made in the chest and a thoracoscope, which is an instrument similar to a telescope and is connected to a video camera, is inserted in the area of the tumor. A doctor can then view the tumor and/or take a tissue (called a biopsy) at this time.

Mediastinoscopy
In a mediastinoscopy, a small incision is made just above the sternum and a lighted tube is placed behind the breast bone. allowing the doctor to view the lymph nodes which can provide clues about the body’s immune system, a tissue sample may be removed at this time. Once removed, the tissue samples are then analyzed under a microscope.

Bronchoscopy
In this procedure, a lighted tube is inserted through the mouth , down the throat and into the bronchi. Abnormal masses or irregular tissue can then be removed (called a biopsy) for testing.

Chest X-Ray
X-ray machines use radiation to take a picture of the lungs or affected area. An x-ray may reveal several types of abnormalities including buildup of fluid in the pleural space, irregular thickening of the pleura and pleural calcifications (mineral deposits). These abnormalities may indicate asbestos exposure and the development of mesothelioma.

CT Scan (Computed Tomography)
Type of x-ray procedure that produces detailed cross-sectional images of the body. Unlike a traditional x-ray that takes a single picture, a CT scanner takes a series of pictures as it rotates around you. A computer then combines these images to create a cross-sectional “slice” of the body. A radiocontrast agent or “dye” may be injected into patient intravenously, which helps define the structures of the body and may help in determining the extent to which the cancer has spread.

MRI Scan (Magnetic Resonance Imaging)
This scan uses radio waves, strong mangnets and a computer to produce a cross-sectional image of the body. The energy from the radio waves and magnets are absorbed and released by the different tissues in the body. In this procedure the patient may be injected with a radiocontrast agent prior to being positioned in the tunnel of the MRI machine.

PET Scan (Positron Emission Tomography)
This scan uses radioactive glucose (sugar) to determine the spread of cancer. Cancer tissue consumes glucose at a much faster rate than normal tissue. When radioactive glucose is injected intervenously into the patient the diseased tissue takes up higher levels of the radioactive material and when scanned, can provide insight into the stage and spread of the cancer.

Source: Connelly & Vogelzang