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Pleural mesothelioma, pleura mesothelioma, or malignant pleural mesothelioma is mesothelioma cancer in the lining of the lungs. This is different from lung cancer, which refers to any type of malignant tumor that originates in the lungs.

The pleura, is the tissue lining or covering that surrounds the lungs. There are two pleura. These can be called pleural membranes. The gap between them is called the pleural space. The pleura are fibrous sheets. They help to protect the lungs. They produce a lubricating fluid that fills the gap between the two pleura. This helps the lungs to move smoothly in the chest when they are inflating and deflating as we breathe.

Pleural mesothelioma is the most common form of mesothelioma accounting for 80-90% of mesothelioma cases.

In general, the clinical presentation of pleural mesothelioma may include the following:

1. Cough
2. Shortness of breath, difficulty breathing
3. Difficulty sleeping
4. Pain in the chest and abdominal regions, which is generally unresponsive to analgesics
5. Progressive loss of appetite and weight loss
6. Pleural effusions (fluid in the chest cavity)

Management of pleural mesothelioma depends largely on the staging of the tumor. Early diagnosis and surgical intervention may lengthen life expectancy. However, surgery may not be a viable option depending on the age and physical condition of the patient. In addition to surgical options, radiation treatment and chemotherapy may be helpful in the overall therapeutic program for treating pleural mesothelioma. Pain management and home care are typical alternatives in the later stages of pleural mesothelioma.

Pleural mesothelioma is of two kinds: (1) diffuse and malignant (cancerous), and (2) localized and benign (non-cancerous.)

Benign pleural mesothelioma can often be removed surgically, is generally not life-threatening, and are not usually related to asbestos exposure. Malignant pleural mesothelioma, however, is very serious. Fortunately, they are rare—about two thousand people are diagnosed with pleural mesothelioma in the U.S. each year.

The remainder of this section focuses on diffuse malignant pleural mesothelioma.

Pleural mesothelioma is a cancer of the cells that make up the pleura or lining around the outside of the lungs and inside of the ribs. Its only known cause in the U.S. is previous exposure to asbestos fibers, including chrysotile, amosite, or crocidolite. This exposure is likely to have happened twenty or more years before the disease becomes evident, since it takes many years for the disease to "incubate." It is the most common type of mesothelioma, accounting for about 75% of all cases.

Pleural mesothelioma is sometimes diagnosed by coincidence, before there are any symptoms. For instance, tumors have been discovered through routine chest x-rays. However, when symptoms occur, they may include shortness of breath, weakness, weight loss, loss of appetite, chest pains, lower back pains, persistent coughing, or difficulty in swallowing. An initial medical examination often shows a pleural effusion, which is an accumulation of fluid in the pleural space—the area between the lungs and the chest wall.

The first step in detecting pleural mesothelioma is, typically, a chest x-ray or CT scan. This is often followed by a bronchoscopy, using a viewing scope to look inside the lungs.

The actual diagnosis usually requires obtaining a piece of tissue through a biopsy. This can be done with a needle biopsy, an open biopsy, or through a tube with a camera (thoracoscopy or chest scope.) If an abnormality is seen through the camera then a tissue sample can be taken at the same time, using the same tube. This is a hospital procedure that requires anesthesia, but is not usually painful. A pathologist then tests the tissue sample.

Fluid build-up from the pleural effusion can generally be seen on a chest x-ray and heard during a physical examination, but a firm diagnosis of pleural mesothelioma can only be made through a biopsy and pathological testing. This is important because there are also benign pleural effusions and other tumors that have a similar appearance to pleural mesothelioma. Diagnosing pleural mesothelioma can be quite difficult; it requires special lab stains, and much experience in understanding them.

The spread of the tumor over the pleura causes pleural thickening. This can reduce the flexibility of the pleura and encase the lungs in an increasingly restrictive girdle. With the lungs restricted, they get smaller and less functional, and breathing becomes more difficult. At first a person with pleural mesothelioma may be breathless only when he or she exercises, but as lung function drops, he or she can become short of breath even while resting.

The tumor spreads by direct invasion of surrounding tissue. As it spreads inward it can compress the lungs. As the tumor spreads outward it can invade the chest wall and ribs, and this can be extremely painful.

Current medical science does not know exactly how and why, at a cellular level, asbestos fibers cause mesothelial cells to become abnormal (malignant or cancerous). Thus it is not known whether only one fiber causes the tumor or whether it takes many fibers. It seems that asbestos fibers in the pleura can start a tumor as well as promote its growth; the tumor does not depend on any other processes for its development.

There is as yet no known cure for malignant pleural mesothelioma. The prognosis depends on various factors, including the size and stage of the tumor, the extent of the tumor, the cell type, and whether or not the tumor responds to treatment. Many clients live for five to ten years after diagnosis, most of them in good health for a majority of those years; however, some pleural mesothelioma victims succumb within a few months. The average survival time is about a year.