- What is it:
- Pleural calcification refers to:
- The deposition of calcium salts within the pleura,
- typically resulting from chronic inflammation, prior injury, or exposure to certain agents.
- It is often associated with:
- Bilateral calcifications: Seen in systemic or environmental exposures like asbestos.
- Unilateral calcifications: Associated with localized conditions like hemothorax or prior infection.
- Etymology:
- Derived from the Latin word calx, meaning “lime,” reflecting the calcium content in these deposits.
- AKA:
- Calcified pleural plaques, Pleural calcinosis.
- How does it appear on each relevant imaging modality:
- Chest X-ray:
- Bilateral calcifications:
- Dense, irregular opacities along the pleura, commonly affecting:
- Lateral chest walls,
- Diaphragmatic pleura.
- Unilateral calcifications:
- May be focal or extensive, typically in the setting of:
- Hemothorax,
- Tuberculosis, or
- Empyema.
- Chest CT:
- Parts:
- Well-defined areas of calcification within the parietal pleura, often sparing the visceral pleura.
- Size:
- Varies from small focal plaques to extensive calcifications involving large portions of the pleura.
- Shape:
- Flat or irregular; may follow the contour of the chest wall or diaphragm.
- Position:
- Bilateral:
- Associated with asbestos exposure or diffuse processes.
- Unilateral:
- Commonly seen in post-traumatic or post-infectious cases.
- Character:
- High-attenuation plaques with or without associated pleural thickening.
- Time:
- Chronic and develops over years following exposure or injury.
- Ultrasound:
- May show hyperechoic plaques with posterior acoustic shadowing.
- MRI:
- Rarely used but may demonstrate low signal intensity corresponding to calcified areas.
- These findings reflect:
- Exposure-related processes:
- Bilateral:
- Asbestos exposure (most common).
- Talc pleurodesis.
- Unilateral:
- Talc pleurodesis (site-specific).
- Post-inflammatory processes:
- Tuberculosis-related pleuritis.
- Chronic empyema.
- Post-traumatic processes:
- Hemothorax with fibrotic healing and calcification.
- Differential diagnosis:
- Benign causes:
- Bilateral:
- Asbestos-related pleural plaques.
- Talc pleurodesis (iatrogenic).
- Unilateral:
- Post-infectious calcifications (e.g., tuberculosis, empyema).
- Post-hemothorax fibrosis and calcification.
- Malignant causes:
- Mesothelioma (rarely associated with calcifications but can occur).
- Secondary calcification in malignant pleural metastases.
- Recommendations:
- Correlate imaging findings with clinical history, including:
- Occupational exposure (e.g., asbestos),
- Prior infections (e.g., tuberculosis), or
- History of hemothorax or pleurodesis.
- Perform Chest CT to assess the extent and distribution of calcifications, noting whether bilateral or unilateral.
- Monitor for progression or associated findings suggestive of malignancy (e.g., pleural masses or effusion).
- Consider biopsy only if calcification is associated with suspicious findings such as nodular thickening or mass lesions.
- Key points and pearls:
- Asbestos exposure is the most common cause of bilateral pleural calcifications, particularly in industrial workers.
- Unilateral calcifications are more frequently associated with trauma, infection, or iatrogenic conditions (e.g., talc pleurodesis).
- Calcified pleural plaques are typically benign and asymptomatic, serving as markers of prior exposure or injury.
- Associated pleural thickening or masses warrant further evaluation for malignancy.
- Talc pleurodesis can produce calcifications and should be considered in post-treatment imaging interpretations.
