Pleural plaques are localized scars (fibrosis) consisting of collagen fiber deposits that form as a result of exposure to asbestos. They are the most common manifestation of exposure to asbestos. Normally, pleural plaque is found in the parietal pleura (on the inside of the diaphragm), but in very rare cases they also can be found near the ribcage.
Pleural plaques first appear around 20 years after a person is exposed to asbestos. Prior to the 1970s, when asbestos regulations came into effect, countless workers in industries such as mining, construction and shipping were exposed to dangerous levels of asbestos. Due to the fact that it takes about 30-40 years for asbestos-related diseases such as asbestosis and mesothelioma to develop, the victims currently experiencing symptoms likely represent the last big wave of occupation-related asbestos disease cases.
Unlike pleural thickening, pleural plaques rarely form for reasons other than asbestos exposure, though some researchers believe inhalation of erionite fibers may lead to the formation of pleural plaques in some cases. (Erionite may be a cause of mesothelioma as well. Refer to our article on erionite and mesothelioma for more information.) As a result, when they appear on a radiograph or CT scan, doctors immediately suspect damage due to asbestos. Approximately 50 percent of people who are exposed to asbestos over prolonged periods of time develop pleural plaque.
All asbestos-related ailments occur because, unlike other airborne particles, asbestos fibers are small enough to subvert the lungs’ natural filtration system and imbed themselves in bodily tissues, where they cause inflammation and scarring.
In contrast to the diseases that commonly go hand in hand with pleural plaques, pleural plaques themselves are not associated with any symptoms. As a result, pleural plaque is often first detected on a radiograph or CT scan. It appears similar to pleural thickening on a radiograph;on a CT scan, it appears as localized areas of pleural thickening that are sometimes described as "mesas" or "table mountains." And on a microscopic level, pleural plaques appear as collagen bundles resembling a basket weave.
Like pleural thickening, pleural plaque is benign (non-cancerous), cannot become malignant and is not necessarily a sign of an asbestos lung disease. However, many people who develop pleural plaques also develop pleural effusion, asbestosis, malignant mesothelioma and other conditions associated with asbestos inhalation.
Pleural plaques can form even with low-dose, intermittent exposure. This stands in contrast to asbestosis, or pulmonary fibrosis, which develops only after a certain dose threshold has been crossed. However, pleural plaques are almost always present in patients with asbestosis and are often present in patients with mesothelioma.
While non-cancerous forms of asbestos lung disease can be treated with medication (for inflammation) and oxygen, malignant mesothelioma is lethal and nearly always worsens and leads to death. Although mesothelioma cancer treatments do exist, mesothelioma treatment largely consists of measures to alleviate discomfort and pain (palliative treatments).
There are three types of mesothelioma: pleural mesothelioma, which affects the lining of the lungs; peritoneal mesothelioma, which is found in the abdominal lining; and pericardial mesothelioma, which affects the lining of the heart. Pleural mesothelioma is the most common.
Mesothelioma is further categorized by the following three cell types:
There is ample evidence to suggest that some companies knowingly exposed their employees to lethal asbestos particles. The willful negligence of these companies often serves as grounds for pleural plaque lawsuits. For more information on pleural plaque lawsuits, contact a mesothelioma attorney.
[Page updated November 2011]