Merck Manual

Please confirm that you are a health care professional

honeypot link

Pleural Fibrosis and Calcification


Najib M Rahman

, BMBCh MA (oxon) DPhil, University of Oxford

Reviewed/Revised Aug 2023
Topic Resources

Pleural fibrosis and calcification are usually benign sequelae of pleural inflammation or asbestos exposure.

Pleural fibrosis and calcification can be either

These disorders are suspected and diagnosed based on imaging studies. Treatment of fibrosis and calcification themselves is generally unnecessary. Rarely, very large areas of fibrosis require surgical removal.


Pleural inflammation commonly causes acute pleural thickening due to fibrosis. In most cases, the thickening resolves almost completely. Some patients are left with minor degrees of pleural thickening, which usually causes no symptoms or impairment of lung function. Occasionally, the lung becomes encased with a thick, fibrous pleural peel that limits expansion, pulls the mediastinum toward the side of disease, and impairs pulmonary function.

Chest x-ray shows asymmetry of the lungs with thickened pleura (trapped lung). Differentiating localized pleural thickening from loculated pleural fluid may be difficult on x-ray, but this differentiation is easily made with CT.

Pleural fibrosis after inflammation can, on occasion, calcify. Calcification produces a dense image on the chest x-ray and almost always involves the visceral pleura. Postinflammatory calcifications are invariably unilateral.


Exposure to asbestos can lead to focal, plaquelike pleural fibrosis, at times with calcification, occurring up to 20 years after the initial exposure.

Diagnosis is usually by chest x-ray. The diameter of the plaques can vary from several millimeters to 10 cm. Any pleural or pericardial surface can be affected, but asbestos-related pleural plaques are usually in the lower two thirds of the thorax and are bilateral. Calcification most often affects the parietal and diaphragmatic pleura and spares the costophrenic sulci and apices. Calcification may be the only evidence of exposure. Dense pleural fibrosis surrounding the entire lung and >1 cm in thickness can also follow asbestos exposure.

NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
quiz link

Test your knowledge

Take a Quiz!