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:
Pleural effusion (excessive fluid in the pleural space)
Tumors (both benign and malignant)
Rheumatoid lung disease
Pulmonary embolisms (blood clots in an artery of the lung)
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 imbedded 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 a 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. 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.
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.
Pleural Thickening and Malignant Mesothelioma
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. In fact, 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.
Pleural thickening is often linked to exposure to asbestos, but it can develop from other sources and the information set out below aims to explain more about the condition.
The pleura - two layered protective membrane surrounding the lung
The lungs - a pair of organs in the chest that control breathing. They take in oxygen from the air that we breathe and remove carbon dioxide from the blood
Pleural thickening - thickening and hardening of the pleura
It can occur in 2 forms:
Diffuse pleural thickening extends over a large area and may restrict expansion of the lungs
Pleural Plaques - localised areas of pleural thickening/calcification which do not usually interfere with breathing