Pleural thickening occurs when scar tissue develops on the lining of the lungs, or the pleura. It may be caused by asbestos exposure. Pleural thickening can indicate serious diseases, such as mesothelioma. Though it cannot be cured, treatment can help manage symptoms.

01. What Is Pleural Thickening?

What Is Pleural Thickening?

Pleural thickening develops when scar tissue thickens the delicate membrane lining the lungs (the pleura). Pleural thickening can develop following asbestos exposure or other conditions, such as infection. It may be a symptom of a more severe diagnosis such as malignant pleural mesothelioma.

Depending on the cause, pleural thickening may form in different parts of the pleura. To distinguish between types, doctors will use imaging scans to examine the patient’s lungs and pleura:

  • Visceral pleura: The membrane directly covering the lung tissue
  • Parietal pleura: The outer membrane of the lung attached to the chest wall
  • Pleural space: The space between the visceral and parietal pleura

The location of the impacted pleura and amount of thickening can help doctors determine the type.

Types of Pleural Thickening
  • Apical pleural thickening: Thickening of the top-most portion of the pleura. This type is benign unless the pleura has thickened more than two centimeters.
  • Focal pleural thickening: Thickening confined to one or more specific areas of the pleura.
  • Diffuse pleural thickening (DPT): Thickening of 50% or more of either the left or right pleura. DPT may also be diagnosed in a patient with thickening of 25% or more of both pleurae.
  • Mesothelioma-specific diffuse pleural thickening: Thickening and scarring of the visceral pleura, which can lead to the collapse of the pleural space.
  • Nodular pleural thickening: Thickening that creates raised bump-like nodules from scar tissue.

Is Pleural Thickening Serious?

Pleural thickening is not always serious. The condition can be serious as it becomes more advanced and limits lung function. Pleural thickening is also often an indicator of a serious underlying condition. For instance, pleural thickening may be a sign of malignant mesothelioma cancer.

In some cases, pleural thickening can be benign. Benign pleural thickening is not caused by cancer and will typically not impede the normal functioning of the lungs. However, benign pleural thickening can impede a patient’s lung function if the thickening becomes too advanced.

Whether malignant or benign, pleural thickening cannot be cured. However, treatment can help manage symptoms.

02. Pleural Thickening and Mesothelioma

How Does Pleural Thickening Relate to Mesothelioma?

Pleural thickening in mesothelioma patients develops as a result of prolonged asbestos exposure. Individuals may ingest or inhale asbestos fibers, which may become trapped in the pleura. There, the fibers irritate the lung lining, causing chronic inflammation.

Over time, this inflammation can lead to severe scarring of the lungs. The accumulating scar tissue can become thick enough to impair the patient’s lungs from properly expanding when trying to inhale.

According to studies, pleural thickening is common among mesothelioma patients.

  • In one retrospective study, researchers reported 88% of malignant pleural mesothelioma patients showed pleural thickening on CT scan images.
  • In several prospective studies, 5 – 13.5% of asbestos workers developed diffuse pleural thickening. The workers developed the condition anywhere from 3 to 34 years after asbestos exposure.
Does Pleural Thickening Only Affect Mesothelioma Patients?

Pleural thickening does not only impact mesothelioma patients. It can be caused by various conditions, including infection and injury. Individuals with asbestos-related diseases besides mesothelioma, such as asbestosis and asbestos lung cancer, may also experience pleural thickening.

03. Symptoms of Pleural Thickening

What Are the Symptoms of Pleural Thickening?

Pleural thickening can be a progressive disease, meaning the symptoms often become more severe over time. In early stages, pleural thickening is often asymptomatic. As such, the condition can be difficult to detect.

Common symptoms of pleural thickening include:

  • Chest pain
  • Cough
  • Difficulty breathing and catching your breath (dyspnea), especially after or during exertion
  • Difficulty or inability to take a deep breath
  • Fatigue
  • Fever
  • Pain when exhaling or inhaling
  • Respiratory failure

Individuals may experience additional symptoms depending on the cause of the pleural thickening.

Individuals experiencing any of these symptoms should contact a doctor. Though pleural thickening alone may not be serious, a doctor can conduct a thorough examination for an underlying cause.

04. Causes of Pleural Thickening

What Causes Pleural Thickening?

Pleural thickening can be caused by infection, asbestos exposure, injury and more. Exposure to lung irritants and infectious diseases are some of the common causes of pleural thickening.

Causes of pleural thickening include:

  • Asbestos
  • Empyema (buildup of pus in the pleural cavity)
  • Hemothorax (excess blood in the pleural cavity)
  • Infection, including tuberculosis or pneumonia
  • Inflammation
  • Injury to the ribs or chest
  • Lung cancer
  • Pleural effusions
  • Pulmonary embolism
  • Tumors (benign or malignant)

The cause can dictate the location, severity and progression of the pleural thickening. For example, pleural thickening caused by asbestos exposure typically develops in the visceral pleura and may be serious. Different causes may also impact which symptoms a patient experiences.

Does Smoking Cause Pleural Thickening?

Pleural thickening is more common among people who smoke or used to smoke than nonsmokers. Research indicates smoking increases the risk of developing diffuse pleural thickening. Smoking limits lung function, but may not be the root cause of pleural thickening.

05. Diagnosis of Pleural Thickening

Diagnosing Pleural Thickening

Pleural thickening is often diagnosed with imaging scans, such as computed tomography (CT) scans. A physical examination may also help diagnose the condition. Often, pleural thickening is diagnosed alongside its cause.

Methods used to detect and diagnose pleural thickening include:

  • Physical examination: A physician will check for physical symptoms, such as altered breathing sounds.
  • Chest X-Ray: Healthy pleurae are not visible on an x-ray, but thickening at the very edges of the lung/pleura may be visible.
  • Computed tomography (CT Scan): CT scans can help detect irregular thickness of the pleura, even at earlier stages where the scar tissue is only a few millimeters thick.
  • Ultrasound: Ultrasounds will only be able to detect thickening more than one centimeter in thickness.
  • Magnetic resonance imaging (MRI): MRIs can be used to detect thickening and other pleural malignancies.
  • Positron emission tomography (PET Scan): Though rarely used, pleural thickening may also appear on a PET scan.

If your doctor believes pleural thickening may be a sign of cancer or another condition, they may order additional tests.

Differentiating Pleural Thickening From Other Pleural Diseases

Pleural thickening may also develop alongside other conditions, such as pleural plaques and pleural effusion. Though these conditions may develop together, they are distinct in how they form and present symptoms.

  • Pleural thickening is the buildup of scar tissue. This can develop in the visceral pleura, the membrane covering the surface of each lung, or the parietal pleura, the lung’s outer membrane that also connects to the chest cavity.
  • Pleural plaques are the buildup of grey/white tissue on the pleura and areas of benign thickening. This condition most commonly develops in the parietal pleura.
  • Pleural effusion is the buildup up of fluid between the pleurae.

It’s important for the doctor to differentiate these pleural diseases to develop the appropriate treatment plan.

06. Pleural Thickening Treatment

How Is Pleural Thickening Treated?

Many cases of pleural thickening do not require treatment, as they are not life-threatening. However, the condition may advance, and patient symptoms may become uncomfortable. In these cases, doctors may recommend pulmonary rehabilitation or cessation of smoking, if applicable.

Pulmonary rehabilitation may be able to improve symptoms and quality of life for patients. A team of specialists will develop a customized plan based on an individual’s needs. Some common recommendations for patients to remedy pleural thickening include:

  • Improving diet and nutrition
  • Exercising regularly
  • Learning breathing strategies
  • Learning how to conserve energy

Doctors may administer pleural thickening treatment in conjunction with treatment for the underlying cause. For mesothelioma patients, medical professionals will often recommend regular respiratory function tests. These tests can determine how well the lungs are working and monitor disease progression.

Doctors will perform respiratory function tests by:

  • Testing the lung volume, or how much air the patient’s lungs can hold
  • Analyzing the diffusing capacity, or the transfer of oxygen to the lungs

With these results, doctors can make recommendations to try to improve lung function and manage symptoms.

Is Pleural Thickening

On its own, pleural thickening is not documented to be fatal.

The condition can be benign, which does not require treatment. The condition can also be a symptom of a larger diagnosis, such as mesothelioma or tuberculosis.

If a scan or examination reveals pleural thickening, a doctor can test for any underlying causes.

Can Pleural Thickening Be Cured?

Pleural thickening does not have a cure. The effects of pleural thickening cannot be reversed. However, the condition may be asymptomatic or have mild symptoms that do not require treatment.

If the disease progresses and symptoms worsen, doctors may recommend various treatment options. For example, doctors may suggest pulmonary rehabilitation to treat symptoms such as breathlessness.

It is important for patients to remember pleural thickening may be a symptom of another, more serious disease. Depending on the diagnosis, treatment recommendations and the patient’s prognosis will vary.