What are the common causes and treatments of pleural calcification?

Pleural Calcification: Causes and Clinical Approach

Primary Answer

Asbestos exposure is the most common cause of pleural calcification, presenting as bilateral calcified pleural plaques typically appearing 20+ years after initial exposure. 1

Common Causes of Pleural Calcification

Asbestos-Related (Most Common)

• Asbestos exposure accounts for the vast majority of pleural calcifications, with multiple bilateral lesions being almost invariably associated with asbestos. 1
• Calcified pleural plaques appear in chest films of 2.3% of U.S. males and are the most common manifestation of asbestos exposure. 1
• Calcification typically develops 20+ years after first exposure, with prevalence directly related to duration from initial exposure. 1
• Central calcification within plaques is common, appearing as sharply demarcated lesions on the parietal pleura, particularly on the lower posterior thoracic wall and diaphragm. 1
• Approximately 85% of heavily exposed workers show pleural thickening (predominantly plaques) more than 40 years from first exposure. 1

Infectious Causes

• Tuberculosis can cause pleural calcification, either as isolated plaques or extensive calcification following tuberculous pleurisy. 1, 2, 3
• Primary pleural tuberculosis with calcification is extremely rare but should be considered in patients with constitutional symptoms (fever, weight loss, cough) even without underlying lung pathology. 2
• Chronic tuberculous pleurisy can lead to significant pleural thickening and calcification if not treated promptly, with fibrin deposition causing adhesions and eventual calcification. 3
• Chronic fungal infections can also result in calcified pulmonary nodules and pleural involvement. 4

Trauma-Related

• Hemothorax and chest trauma can result in isolated pleural calcification. 1
• Post-traumatic pleural calcification typically presents as unilateral findings, distinguishing it from the bilateral pattern of asbestos exposure. 1

Other Causes

• Empyema in childhood or following acute pleuritis can result in diffuse pleural thickening that may calcify over time. 1
• Cardiac surgery and thoracic procedures can lead to pleural calcification. 1

Distinguishing Features by Etiology

Asbestos Pattern

• Multiple bilateral lesions with classic appearances (sharply circumscribed, raised, smooth or knobby surface) are pathognomonic for asbestos exposure. 1
• Plaques spare the costophrenic angles and apices, appearing on the midlateral chest walls between the fourth and eighth ribs. 1
• Calcification appears as sharp, foliate borders when seen face-on and irregular margins when seen in profile. 1

Tuberculosis Pattern

• May present as isolated plaques or extensive crescent-shaped calcification. 2, 3
• Often unilateral initially, though can become bilateral. 3
• Associated with history of tuberculous pleurisy or constitutional symptoms. 2, 3

Trauma Pattern

• Typically unilateral and localized to the site of injury. 1
• History of hemothorax or chest trauma is key to diagnosis. 1

Clinical Implications and Management

Functional Impact

• Pleural calcification, particularly from asbestos, can cause restrictive lung disease with approximately 5% reduction in FVC even without interstitial fibrosis. 1
• Diffuse pleural thickening with calcification has greater functional impact than circumscribed plaques, with reductions of 270 ml in FVC. 1
• Restrictive impairment with relative preservation of diffusing capacity is characteristic. 1

Malignancy Risk

• Presence of asbestos-related pleural plaques indicates elevated risk of mesothelioma and lung cancer, serving as a marker for significant asbestos body burden. 1
• This increased risk is due to greater exposure/retained body burden, not malignant degeneration of the plaques themselves. 1

Diagnostic Approach

• Plain chest radiography is sensitive and appropriate for initial detection of pleural calcification. 1
• HRCT is useful for questionable abnormalities and distinguishing pleural plaques from subpleural fat or other mimics. 1
• Proper film penetration is critical—calcification may not be apparent on underpenetrated films. 1

Critical Pitfalls to Avoid

• Do not mistake subpleural fat for pleural plaques—fat pads typically occur in the midthoracic wall with gradually tapering edges, while true plaques have sharp, cut-off edges. 1
• Do not assume all pleural calcification is benign—obtain detailed occupational and exposure history to assess malignancy risk. 1
• Do not overlook tuberculosis as a cause, particularly in patients with constitutional symptoms or endemic areas, even with isolated pleural findings. 2
• Recognize that isolated pleural calcification may be from tuberculosis, trauma, or hemothorax, but multiple bilateral lesions with classic appearance are almost always asbestos-related. 1

Treatment Considerations

There is no specific treatment for pleural calcification itself—management focuses on the underlying cause and monitoring for complications. [1-1]

• For asbestos-related calcification: surveillance for malignancy development and pulmonary function monitoring. 1
• For tuberculous etiology: appropriate anti-tuberculous therapy if active disease is present. 2, 3
• Surgical decortication may be considered for extensive pleural thickening causing significant restrictive physiology, though this is rarely indicated for calcified plaques alone. 1