What Is Pleural Thickening?

Pleural thickening is a condition that causes calcification of the membrane lining the lungs (pleura). It can be a sign of asbestos exposure. This thickening is the result of fibrosis or scarring on the pleura surrounding the lungs. As the scarring becomes more rigid, it makes it difficult for the lungs to expand when breathing. This leads to common pleural thickening symptoms such as shortness of breath and chest pain.

pleural thickening's effect on the lungs

Asbestos may not always cause pleural thickening. But it is an asbestos-related disease. Most cases of mesothelioma also have pleural thickening. This makes diagnosing the two conditions difficult.  

Types of Pleural Thickening

Pleural thickening can be divided into two main categories: Focal and diffuse. Within these groups, specific cases can either be benign or malignant.

  • Focal Pleural Thickening: Thickening in one specific area of the pleura.
  • Diffuse Pleural Thickening: Smooth and uninterrupted thickening that is seen on imaging scans taking up 50% or more of the left or right pleura, or 25% of both pleurae.
  • Benign Pleural Thickening: Non-cancerous thickening of the pleura. The buildup of fibrous tissue is the main cause.
  • Malignant Pleural Thickening: Cancerous thickening of the pleura because of mesothelioma or metastatic cancer from another site in the body.

Pleural thickening can develop in different parts of the lung, on one side or both. Apical pleural thickening refers to thickening in the top portion of the lung. Unilateral pleural thickening means the condition affects either the left or right lung. Bilateral affects both lungs. Your doctor may use these terms when referring to your specific case.

What Causes Pleural Thickening?

Asbestos exposure is one of the primary causes of pleural thickening. Asbestos dust contains microscopic mineral fibers that become lodged in the pleura when inhaled. This causes inflammation, leading to fibrous scar tissue buildup and, eventually, pleural thickening. But any disease that causes acute inflammation of the pleura can lead to pleural thickening.

Other pleural thickening causes include:
  • Infections, such as tuberculosis or chronic pneumonia
  • Empyema, or accumulation of pus in the pleura because of infection
  • Hemothorax, or accumulation of blood in the pleura because of chest injury
  • Radiation exposure
  • Lung cancer
  • Coronary artery bypass grafting surgery

It is important to discuss your health history with your doctor so they are aware of your risk for pleural thickening. Asbestos exposure is the most common cause. But any of these factors can lead to inflammation and eventual pleural thickening. 

What Are Common Pleural Thickening Symptoms?

The most common pleural thickening symptom is shortness of breath. In one study, almost 43% of participants reported this symptom, along with cough, chest pain and fever.

Pleural thickening symptoms include:
  • Breathlessness
  • Difficulty drawing a deep breath
  • Shortness of breath, even with mild exertion
  • Chest pain while drawing a deep breath
  • Pain with coughing
  • Dull, chronic chest pain

If you experience any of these symptoms, especially if you have had significant asbestos exposure, it is important to talk to your doctor. Early detection and diagnosis are the best ways to ensure you receive proper treatment, which can help prevent the condition from progressing further.

How Is Pleural Thickening Diagnosed?

The most common way to diagnose the condition is with imaging studies, such as X-rays, MRIs or CT scans. If you are unsatisfied with your screening results, you can always get a second opinion on the diagnosis.

To help ensure an accurate diagnosis, it is vital to share your history of possible asbestos exposure with your doctor. One review of multiple studies found that pleural thickening occurs in 5% to 13.5% of asbestos-exposed workers. The condition may develop within one year of exposure, or it may arise several years later.

film chest X-ray PA upright : show pleural effusion at right lung due to lung cancer.
Imaging scans can show signs of pleural effusion.

If you are experiencing pleural thickening symptoms, talk to your doctor. They will likely run diagnostic tests.

These screening tests are also used to eliminate the possibility of other diagnoses, such as pleural plaques. These should not be confused with pleural thickening. But asbestos exposure causes both conditions.

X-ray Imaging Scans

Pleural thickening is usually first spotted through a chest X-ray. In fact, it is commonly found in routine chest X-rays along the edges of the lung. This is because the X-ray beam passes through the edges tangentially (not straight through) so it is easier to visualize. 

Fat along the pleura (extrapleural fat) may also look like pleural thickening, which may lead to a misdiagnosis. With this, X-ray images are not the most accurate. To confirm a pleural thickening diagnosis, other imaging techniques may be used. 

CT Scans

Computed tomography (CT) scans are the primary imaging method for diagnosing pleural thickening, pleural plaques and asbestosis. This method is highly sensitive because it uses a contrast agent injected into the veins to help radiologists visualize the pleura. CT scans also take multiple high-resolution images at several angles (planes), providing more detail than chest X-ray images. 

CT scans measure pleural thickening less than 1 centimeter (cm), which can help diagnose early cases. It is also used to diagnose malignant pleural mesothelioma. However, the contrast agent may not be used in patients with poor kidney function or those who are allergic. 

PET Scans and MRIs

Doctors can use positron emission tomography (PET) scans and magnetic resonance imaging (MRI) scans to distinguish between pleural thickening and pleural mesothelioma. Pleural mesothelioma is cancer affecting the pleura and is often associated with asbestos exposure. 

PET scans use radiolabeled glucose molecules to look at tissues that are metabolically active. Tumors are generally active and they take up the glucose molecules, which appear as bright spots on the PET scan. MRIs use a gadolinium contrast agent to help determine whether a patient has pleural thickening or pleural mesothelioma. If a patient cannot have the contrast agent used in CT scans, an MRI is a useful option for diagnosis.

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Pleural Thickening Treatment

Generally, treatment is not required as pleural thickening rarely causes severe symptoms. The most beneficial options are typically to quit smoking, maintain an active lifestyle and undergo pulmonary rehabilitation. In rare cases of severe breathlessness, surgery may be considered.

Some reports have shown pleurectomy surgery to be effective in progressive cases. This aggressive treatment, usually reserved for patients with pleural mesothelioma, involves removing parts of the pleural lining surrounding the lungs.

Pulmonary Rehabilitation

Pulmonary rehabilitation is a supervised exercise program developed for people with lung diseases. It focuses on helping patients regain strength and stamina through breathing techniques, exercises and nutritional counseling. Programs typically last several weeks to months. 

Pulmonary rehabilitation has been shown to help those with pleural thickening recover from their condition. One Australian study found that this program can significantly improve quality of life for patients with dust-related respiratory diseases, including pleural thickening.

Smoking Cessation

For patients who smoke, quitting is essential after a diagnosis of pleural thickening. Smoking further reduces lung function. It also increases the risk of developing other respiratory diseases. As a result, this can aggravate pleural thickening and lead to worsening symptoms.  

Need help quitting? Your doctor can provide supportive care. Nicotine replacements or medications can help curb cravings. Following these steps can improve your odds of successfully quitting for good.

Pulmonologists and pleural specialists have the expertise to diagnose and treat pleural thickening. They can recommend follow-up care and watch the condition for signs of progression.

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Is Pleural Thickening Serious?

Pleural thickening is not always a serious health concern. However, if left untreated, pleural thickening can progress to advanced stages, which may lead to the encasement of the lung and cause restrictive lung disease. This can significantly impact breathing and thus requires attention.

The condition alone is not enough to confirm a pleural mesothelioma diagnosis. But it can be a sign of serious and significant asbestos exposure. It is important to note that not every mesothelioma patient has pleural thickening. 

Catching mesothelioma at an early stage can offer more treatment options. Because an early diagnosis is critical, patients with asbestos-related pleural thickening should have regular cancer screenings.

Common Questions About Pleural Thickening

Does pleural thickening lead to mesothelioma?

Pleural thickening alone is not enough to confirm that you have asbestos cancer. However, it can be a sign of significant asbestos exposure and indicate a high risk for mesothelioma. Advanced pleural thickening can cause restrictive lung disease with severe breathing difficulty.

Can pleural thickening be cured?

Pleural thickening has no cure and is usually limited to supportive treatment. The effects of pleural thickening are irreversible in malignant pleural mesothelioma. Surgery may be an option in some cases to improve breathing difficulty and other respiratory symptoms.

Can smoking cause pleural thickening?

Asbestos is the primary cause of pleural thickening. There is data that points to a correlation between smoking and the progression of pleural thickening. Smoking limits lung function and is proven to be a cause of other respiratory diseases such as lung cancer.