Ask An Expert: Thickening of Lining of the Lungs

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Ask An Expert: Thickening of Lining of the Lungs

Question:

What could cause thickening of lining of the lungs?

Answer:

The lining of the lungs, or pleura, allows the lungs to expand and deflate smoothly during breathing. The finding of pleural thickening is common and is usually discovered by chest X-ray or CT scan. It can be of no consequence (as with mild scarring from pneumonia many years ago) or it can be a sign of serious illness.

Here are some of the more common causes:

• Infection – For example, bacterial pneumonia that causes inflammation of the pleura (pleuritis) can lead to scar tissue and thickening; tuberculosis can also cause pleural thickening.

• Inflammation of the pleura without infection - For example, this is relatively common among people with lupus, an autoimmune disease in which the pleura is just one of many parts of the body that may become inflamed.

• Injury – For example, people who have survived a serious motor vehicle accident may have a "bruise" (called a lung contusion) with bleeding around the pleura that eventually becomes scarred and thickened as it heals; lung surgery is another type of trauma that may lead to scarring and thickening of the pleura.

• Medications – Examples of drugs that can cause pleural thickening include cyclophosphamide (most commonly used as chemotherapy) and amiodarone (used to treat abnormal heart rhythms).

• Pulmonary embolism (a blood clot in an artery in the lung) – This condition can cause death of part of the lung, and pleural thickening may accompany the healing process.

• Radiation – Most commonly pleural disease due to radiation occurs after radiation therapy for cancer in or near the lung.

• Occupational exposures, particularly asbestos – Decades after significant asbestos exposure (for example, among shipbuilders, pipe fitters and insulation workers), about 50 percent of people will develop pleural "plaques," small areas of thickening triggered by asbestos fibers. Asbestos exposure is also a risk factor for mesothelioma (see below); other inhaled occupational exposures, such as beryllium, can trigger pleural scarring as well.

• Tumors – Benign and cancerous tumors may involve the pleura and cause thickening; when cancer affects the pleura it has usually spread there from elsewhere rather than originating there, although mesothelioma can begin in the pleura.

Given the range of possibilities, it is important to have a thorough evaluation with a physician who knows your medical history, risk factors for lung disease, and the results of your lung imaging tests.

Robert Shmerling, M.D., is associate physician and clinical chief of rheumatology at Beth Israel Deaconess Medical Center and an associate professor in medicine at Harvard Medical School. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program and has been a practicing rheumatologist for over 25 years.

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Last updated:	January 24, 2007