What Are Pleural Plaques?

X-ray of calcified asbestos pleural plaques
Close-up X-ray of calcified asbestos pleural plaques. The translucent white areas behind the rib cage show the pleural plaques.

Pleural plaques are areas of thickened tissue that form in the lining of the lungs. This plaque is a noncancerous asbestos-related condition.

Pleural plaques may increase cancer risk for pleural mesothelioma or asbestos lung cancer. The plaques themselves do not lead to cancer.

The pleura is the thin membrane that surrounds the lungs and envelops the inside of the chest. Thickened tissue can develop on both layers of the pleura after asbestos exposure.

The majority of people with pleural plaques do not show obvious symptoms. But some patients describe pain or an uncomfortable, grating sensation as they breathe.

Pleural plaques are also called hyaline pleural plaques. They contain hyaline tissues found in cartilage.

What Causes Pleural Plaques?

Asbestos exposure is the primary cause of pleural plaques. The thick pleural tissue does not always lead to mesothelioma.

Breathing in asbestos fibers causes them to build up in the lung lining and irritate lung tissue. Studies show fibers reach the pleural space through the lymph system.

Research suggests asbestos fibers cause an immune response of cells called pleural macrophages. These cells trigger inflammation that leads to fibrosis.

Fibrosis occurs when connective tissue replaces normal, healthy lung tissue with collagen fibers. These fibrous areas are sometimes called scar tissue.

Quick Fact:
In 20% of cases, pleural plaques become calcified. As calcium deposits build, the scar tissue hardens. Calcified pleural plaques rarely inhibit lung function and cause patients to have trouble breathing.

Where Do Pleural Plaques Develop?

Pleural plaques often develop on the parietal pleura that lines the inside of the rib cage. In rare cases, they may form on the visceral pleura, which lines the lungs.

These hyaline growths can also form on the diaphragm. This muscle controls breathing and respiration. The plaques are often localized and don’t spread to distant areas.

What Are the Symptoms of Pleural Plaques?

Pleural plaques do not usually cause any symptoms.

Recent evidence shows they sometimes cause a slight decrease in total lung capacity. Plaques may also affect other measures of lung function.

Asbestos-exposed patients with pleural plaques may develop pleural thickening. This condition affects a larger area and can prevent the lungs from expanding.

Pleural thickening can cause difficulty breathing, persistent or bloody cough or chest pain. These may also be signs of a more severe and undiagnosed condition.

Notify your doctor if you experience any symptoms. Your doctor may refer you to a specialist for more severe breathing issues.

How Are Pleural Plaques Diagnosed?

Doctors diagnose pleural plaques using imaging scans such as X-rays or CTs. For many people, pleural plaques appear incidentally during routine tests. Doctors often identify the plaques by chance during chest imaging for other illnesses.

Discovery Through X-ray

Radiologists find most plaques after an X-ray. This test reveals areas with thickened nodular edges resembling a holly leaf. In specific locations, the condition can be difficult to identify via X-ray.

Calcified pleural plaques appear as translucent white deposits on the lungs. Plaques are often asymptomatic but are a sign of asbestos exposure. Over time, this exposure can lead to pulmonary fibrosis or asbestos-related malignancies.

Diagnosis with CT Scan

A CT scan is the preferred method for diagnosing this condition. A CT is 95% to 100% accurate for identifying this condition. The test can reveal plaques anywhere in the chest, even if they are not calcified.

After diagnosing pleural plaques, your doctor will review other signs of asbestos-related disease. They will customize a unique treatment plan if you have an asbestos-related illness.

Quick Fact:
Doctors typically diagnose this condition using a chest X-ray or CT scan. Because it rarely causes symptoms, they usually find it incidentally after performing an imaging scan for an unrelated reason.

Prevalence and Risk of Developing Pleural Plaques

Estimating the exact prevalence of pleural plaques is challenging. Most people with past exposure are not screened for these fibrous pleural changes.

A 2022 case study identified several outstanding diagnostic factors of mesothelioma. These included bilateral pleural plaques, nodules and pleural effusion.

A 2017 study examined 1,512 CT scans. The researchers noted 76, or 5.1% of the images, showed the presence of pleural plaques. In about 17% of these patients, doctors ordered the CT due to possible prior asbestos exposure.

In contrast, a 2018 Japanese study found pleural plaques on 89.4% of CT scans after asbestos exposure. These findings suggest pleural plaques are not typical for the general public.

The research suggests that asbestos exposure is a direct cause of pleural plaques. This evidence supports the connection between asbestos exposure and pleural plaques. It also highlights the benefit of yearly low-dose CT screenings.

How Are Pleural Plaques Treated?

Doctors do not treat pleural plaques as a standalone illness. They are noncancerous, and most patients do not experience a loss in lung function.

If you have pleural plaques, these steps can prevent further damage:

  • Quit Smoking: Ask your doctor for help with a smoking cessation program.
  • Avoid Further Asbestos Exposure: If you must work around asbestos, use personal protective equipment such as a respirator and disposable coveralls.
  • Minimize Exposure to Air Pollution: If you live in an area with wildfires and other sources of heavy air pollution, heed warnings to stay indoors when pollution levels are highest.

Find a Specialist Near You

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Dr. Edmund K. Moon
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Dr. Andrew Haas
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Dr. Anthony R. Lanfranco
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Dr. Francis D. Sheski
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Are Pleural Plaques Related to Cancer?

Some research suggests pleural plaques increase your risk of cancer. The fibrous thickening raises the risk of pleural mesothelioma. Data shows pleural plaques also have a higher risk of leading to lung cancer than smoking.

Doctors may estimate cancer risk based on asbestos exposure. They’ll review the amount, duration, and time since the initial exposure.

Plaques can harden over time but do not cause long-term health problems for most people. Frequent or extended asbestos exposure can cause more severe noncancerous illnesses, such as asbestosis.

Tell your provider about past asbestos exposure. The details could inform your doctor whether to test for other asbestos-related diseases.