Asbestos exposure can cause medical conditions other than mesothelioma. Pleural plaques, like mesothelioma, usually develop after a latency period of at least 20 years. However, they have been reported cases in which the disease developed in less than ten years after the initial exposure to asbestos. Patients with pleural plaques do not exhibit any specific symptoms.
What are Pleural Plaques?
Pleural plaques are benign collagen fiber deposits that appear glass-like. They are caused by the inflammation that results from inhaled asbestos fibers that have not been released through the body’s own defense mechanisms.
Where do Pleural Plaques Form?
These collagen deposits are primarily found in the parietal pleura, which is the part of the pleura that connects to the chest wall. One explanation for this specific location is that asbestos fibers are carried to the surface of the pleura by the lymphatic system. This explanation has been supported by the observation that pleural plaques are situated near the openings where the asbestos fibers are reabsorbed into the flow of lymphatic liquid. The other explanation for their location is that the fibers directly penetrate the parietal surface after inhalation.
Not only do pleural plaques form on this specific part of the pleura, they do so next to stiff structures, like the ribs; especially the sixth through the ninth ribs. They can also be found along other rigid structures such as the central tendon of the diaphragm and the vertebrae of the spine.
Pleural plaques typically do not form on the:
- Visceral pleura, which is the part of the pleura that covers the lung
- Spaces between the ribs
- Space between the ribs and the furthest side of the diaphragm
- Tips of the lungs
Do Pleural Plaques Change over Time?
Calcium deposits usually develop in pleural plaques. At first, they look like tiny specs and then over time they merge together to form dense deposits. These calcium deposits are found in 20 percent of all patients after an x-ray. Computed Tomography (CT) scans are successful in identifying them in about one out of two patients. However, pleural biopsy can identify them in approximately 80 percent of patients who have them.
Is There a Treatment for Pleural Plaques?
There is no cure for this condition, which will typically worsen over time. However, the presence of pleural plaques does not mean the patient will necessarily develop lung cancer or mesothelioma.
Pleural plaques are not life threatening and are treated only if lung function has decreased because of their presence. The goal of treatment is to relieve the pressure on the lung that is causing it to function poorly.
Research Suggests that Follow up for Patients with Asbestos Exposure Should be Based on the Length of Exposure Time, not the Presence of Pleural Plaques
In an article titled “Asbestos-Related Cancer Risk in Patients with Asbestosis or Pleural Plaques”, published June 2011 in Revue des Maladies Respiratoires (Review of Respiratory Diseases), researchers noted that:
“Among asbestos-exposed individuals, those having radiographic (chest x-ray) evidence of pleural plaques are at increased risk for lung cancer and pleural mesothelioma, compared to the general population. However, there is no evidence that pleural plaque confers an increased risk of lung cancer or pleural mesothelioma within a population of individuals having the same cumulative asbestos exposure.”