Pleural Thickening and Malignant Mesothelioma

Pleural thickening is the term used to describe the appearance of “diffuse” (widespread) scarring along the lining (pleura) of the lungs. When this pleural scarring (pleural fibrosis) is limited to one location (focal scarring), it is called pleural plaque. While pleural thickening is relatively harmless in some cases, it is also common among workers who were exposed to and inhaled a significant amount of dangerous asbestos particles. Before the 1970s, before asbestos regulations were put in place, the use of asbestos was prevalent in industries such as mining, shipping, construction, and others. Pleural thickening appears in about half the people known to have inhaled asbestos over long periods of time.

Pleural thickening can cause shortness of breath and adversely affect the lungs’ ability to function correctly. It is not malignant and is not necessarily a sign of asbestos lung disease; in this sense, pleural thickening is not as dangerous as asbestosis or malignant mesothelioma. However, it is often a sign of exposure to asbestos, and many people whose lungs show pleural thickening develop asbestos lung diseases. Whether a person with pleural thickening will contract an asbestos-related disease is unpredictable.

Causes of Pleural Thickening

Pleural thickening can occur as a result of any inflammation occurring in the lungs. In addition to asbestos exposure, this may stem from any of the following:

  • Bacterial pneumonia
  • Pleural effusion (excessive fluid in the pleural space)
  • Infection
  • Tuberculosis
  • Tumors (both benign and malignant)
  • Rheumatoid lung disease
  • Radiation therapy
  • Chemotherapy
  • Lung contusions
  • Pulmonary embolisms (blood clots in an artery of the lung)
  • Drugs
  • Lupus

Lupus and pleural thickening often go hand in hand because lupus so often causes inflammation of bodily tissues.

Pleural Thickening Due to Asbestos Exposure

Asbestos-related pleural thickening occurs because, unlike most airborne particles, asbestos fibers are so small that they can bypass the lungs’ filtration system and get into the lungs. Once in the lungs they become embedded in the pleura and other areas, such as the interstitium, and cause inflammation and scarring.

Diagnosis of Pleural Thickening

Pleural thickening can be detected by chest ultrasonography, which produces an image in which pleural thickening appears distinct from other conditions, such as pleural fluid and whitening, the latter of which is a sign of asbestosis (asbestos-caused lung fibrosis). Pleural thickening can also be detected by a CT scan, where it appears as a layer of tissue density between the chest wall and the lungs. (An HRCT scan can detect as little as 1-2 mm of thickening.) The degree of thickening helps doctors determine whether the cause is benign or malignant (cancerous). The appearance of nodules, circumferential thickening (thickening with well-defined borders) and thickening of more than 1 cm may be a sign of malignancy.

Pleural thickening is not in itself a sign of asbestos disease. However, it is a sign of exposure to asbestos and often accompanies asbestos diseases. Sometimes it is detected at the same time as asbestosis or mesothelioma.

Although potentially very serious, asbestosis is not malignant and can sometimes be treated with medications to reduce inflammation, as well as oxygen to help with the breathing difficulties that often arise as a result of damage to the lung.

In contrast, mesothelioma is a very lethal form of cancer that almost always worsens immediately and leads to death; while traditional mesothelioma cancer treatment is used to combat mesothelioma, it cannot stop the disease’s progression, so other “palliative” mesothelioma treatment is also employed to reduce discomfort.

There are three types of mesothelioma:

  • Pleural mesothelioma (mesothelioma of the lungs’ lining, or pleura)
  • Peritoneal mesothelioma (mesothelioma of the abdominal lining, or peritoneum)
  • Pericardial mesothelioma (mesothelioma of the heart lining, or pericardium)

Mesothelioma is also classified by cell type. There are three kinds of mesothelioma cells: epithelioid mesothelioma cells, sarcomatoid mesothelioma cells, and biphasic mesothelioma cells.

For more information on mesothelioma, asbestosis and other asbestos lung diseases, visit our pages devoted to these topics. If you believe you or a loved one has one of these diseases, you should strongly consider contacting a mesothelioma lawyer immediately.

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