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Pleural Plaques

Pleural plaques are the result of an accumulation of hyalinized collagen in the lining of the lungs (pleura), according to a University of California San Diego Professor of Radiology. They are nearly always caused by asbestos but may have a latency period of up to 20-30 years after initial exposure. Unlike the deadly cancer mesothelioma, pleural plaques are benign (non-cancerous).

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What Are Pleural Plaques?

Pleural plaques are chalky buildups of collagen, a protein naturally found in the body. Pleural plaques usually develop as part of the body’s natural immune response being exposed to asbestos.

When asbestos fibers are inhaled or swallowed, the body’s immune system attempts to eliminate them. However, asbestos fibers are so strong that they can never be broken down and so small that they cannot be removed.

While asbestos fibers can settle in different parts of the body, pleural plaques can form when they settle in the pleura (the lining of the lungs).

There are two parts of the pleura:

  • The parietal pleura: This part of the pleura lines the diaphragm and chest wall. Most pleural plaques develop here.
  • The visceral pleura: The visceral pleura lines the inside of the lungs. Though rare, pleural plaques can also develop in this part of the pleura.

These fibers slowly irritate healthy lung tissue depending on where they settle in the pleura. Over time, the body’s immune response to these fibers causes pleural thickening, the hardening of collagen, and the formation of scar tissue.

Pleural plaques rarely cause symptoms, but in some cases, chest pain when breathing or a persistent cough may be reported. These symptoms are generally mild.

Are Pleural Plaques Harmful?

No — unlike some other asbestos-related diseases, pleural plaques are generally not harmful.

Most doctors suggest that patients with pleural plaques do not need any form of medical intervention.

However, because pleural plaques often develop due to past exposure to asbestos, they may mean victims have an increased risk of related conditions, including asbestos-related lung diseases or malignant (cancerous) mesothelioma.

Quick Facts About Pleural Plaques

  • Pleural plaques are known as a marker of asbestos exposure, according to a 2017 report published in BioMed Research International. A marker can help doctors confirm that someone was exposed to asbestos.
  • They are the most common asbestos-related disease, according to a 2011 study published by ScienceDirect.
  • Pleural plaques occur in 50% of people who suffered from long-term asbestos exposure, according to the American Academy of Family Physicians.
  • Pleural plaques are typically not found in the general population, though the true incidence rate is unknown due to a lack of screenings.

Causes of Pleural Plaques

Researchers believe that asbestos exposure is the main cause of pleural plaques.

In most cases, pleural plaques will develop only after prolonged asbestos exposure. Because of this, those who regularly worked in asbestos-heavy jobs are at a higher risk of pleural plaques.

Workers with a higher risk of asbestos exposure include:

  • Boilermakers
  • Construction workers
  • Factory workers
  • Firefighters
  • Industrial workers
  • Miners
  • Military veterans
  • Shipbuilders
  • Steel mill workers
  • Textile mill workers

These workers had a high risk of asbestos exposure prior to the early 1980s because it was not until this time that widespread restrictions on the mineral began.

It is also possible to have secondary asbestos exposure, which could happen when a spouse breathed in asbestos fibers when they washed the clothes of a construction worker, for example.

Studies have found that a high rate of patients with malignant mesothelioma and other asbestos-related diseases also have pleural plaques.

Other Possible Causes of Pleural Plaques
A 2019 report from researchers at the Icahn School of Medicine at Mt. Sinai also suggested that talc may possibly contribute to the development of pleural plaques. Asbestos fibers have been found in some samples of talc products like baby powder.

How Pleural Plaques Form

The development of pleural plaques seems to be almost entirely due to the body’s inability to dislodge or expel asbestos fibers.

When asbestos fibers are inhaled into the pleura, they get stuck in the body and irritate the surrounding tissues. The pleura can become inflamed, and the tissue damage causes the immune system to react.

The body attempts to use proteins such as collagen to cover the damaged tissue. Since the lodged asbestos fibers cannot be removed by the body, the collagen builds up in the damaged tissue area.

The tissue then hardens and forms pleural plaques. That said, pleural plaques do not develop immediately.

Like all asbestos-related diseases, pleural plaques have long latency periods, meaning it can take decades for them to present after someone was first exposed to asbestos.

Symptoms of Pleural Plaques

Typically, pleural plaques do not cause any symptoms at all. If symptoms are experienced, they are generally mild.

Symptoms of pleural plaques may include excessive coughing and pain while breathing and coughing.

Did You Know?

Some researchers believe that significant pleural plaque buildup may also be associated with slightly diminished lung function.

That said, it is very rare that an individual with pleural plaques experiences severe shortness of breath. If shortness of breath is continually present, a medical professional should be consulted to determine if another illness or disease is the cause.

Diagnosis of Pleural Plaques

Since pleural plaques are usually asymptomatic, a diagnosis only comes after an individual visits a physician for other reasons, in most cases.

Pleural plaques can be found using these diagnostic techniques:

  • Biopsies
  • Computerized tomography (CT) scan
  • X-rays
Pleural Plaques May Go Unnoticed
Patients can live with pleural plaques for decades without even knowing that they have them, and they likely wouldn’t know unless they had an X-ray or CT scan for another, unrelated condition.

X-Rays and Pleural Plaque Diagnosis

Through a chest X-ray, radiologists use electromagnetic waves to see inside the chest and chest wall.

If pleural plaques or strange masses show up in the pleural space, patients should ask their medical providers about the risk of lung cancer or mesothelioma.

A medical provider can best assess a patient’s risk and determine if they require further testing for other asbestos-related diseases.

CT Scans and Pleural Plaque Diagnosis

Through a CT scan, radiologists take a series of high-resolution X-ray images to get a more in-depth look inside the body.

Doctors can typically find masses on the lungs or pleura, but these diagnostic tests cannot always determine whether the mass represents cancer or a benign pleural plaque. This is where biopsies come into play.

Biopsies and Pleural Plaque Diagnosis

Through a biopsy, doctors take a small sample of the mass to determine if the tissue is cancerous or a pleural plaque. A biopsy is the only way to determine if cancer is present or not.

Once a biopsy has been confirmed, health care professionals can recommend treatment plans.

Treatment & Prognosis for Pleural Plaques

In the overwhelming majority of pleural plaque cases, treatment is not necessary.

People can live with pleural plaques for decades with no symptoms, and they can live full and healthy lives without any reduced lung function or capacity.

Most doctors believe that the pleural plaques themselves are unlikely to progress and impede breathing.

Likewise, the prognosis — or expected health outlook — for patients with pleural plaques is usually positive.

Although pleural plaques alone do not require any type of treatment, it is important to remember that a diagnosis could indicate a higher risk factor for other asbestos-related diseases like mesothelioma in some cases.

Pleural Plaques and Mesothelioma

There is no direct link between the presence of pleural plaques and mesothelioma. However, both conditions are related to asbestos exposure.

Any individual who has had prolonged exposure to asbestos is at greater risk of both pleural plaques and mesothelioma. That is because of the asbestos fibers that get lodged in the lungs and cause damage to the pleura tissue.

Did You Know?

Asbestos exposure even decades ago can lead to the development of pleural plaques or mesothelioma today.

Patients who worked in a high-risk occupation for asbestos exposure such as mining or construction work — or who have developed pleural plaques — should speak with their doctor about the risk of mesothelioma and what they can do to protect themselves.

While there is no way to undo the health risks associated with asbestos exposure, doctors can recommend the next steps to take if possible symptoms of more serious diseases develop.

Next Steps for Patients with Pleural Plaques

While pleural plaques themselves are not dangerous, they could be an early risk factor for more dangerous asbestos diseases.

You should speak with a doctor immediately if you worked in a job that exposed you to asbestos. Doctors can help you determine if you have pleural plaques — or other pleural diseases — and what treatment options are available to you.

The Mesothelioma Justice Network also has a support team that can answer any questions you may have about pleural plaques and mesothelioma.

We can help you:

  • Assess your options for medical treatment
  • Find top mesothelioma doctors in your area
  • Figure out if you can receive financial compensation after a diagnosis

See all the ways we can help you and your family today.

Mesothelioma Support Team
Reviewed by:Dr. Assuntina Sacco

Board-Certified Oncologist

  • Fact-Checked
  • Editor

Assuntina Sacco, MD is an Associate Professor of Internal Medicine at the University of California, San Diego (UCSD) Moores Cancer Center, where she also serves as the Medical Director of Infusion Services. She is a board-certified medical oncologist trained to treat all solid tumor types, with the use of chemotherapy, immunotherapy, targeted therapy, and clinical trials.

Dr. Assuntina Sacco is an independently paid medical reviewer.

Stephanie KiddWritten by:

Editor-in-Chief

Stephanie Kidd grew up in a family of civil servants, blue-collar workers, and medical caregivers. Upon graduating Summa Cum Laude from Stetson University, she began her career specializing in worker safety regulations and communications. Now, a proud member of the American Medical Writers Association (AMWA) and Editor-in-Chief of the Mesothelioma Justice Network, Stephanie serves as a voice for mesothelioma victims and their families.

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