How does it appear on each relevant imaging modality:
Chest X-ray:
Appear as bilateral areas of calcification or thickening, typically along the lateral chest wall, diaphragm, or mediastinum.
Calcified plaques may appear as irregular dense areas in the pleural space.
Chest CT:
Parts: Localized, well-defined areas of pleural thickening; may involve parietal pleura, sparing the costophrenic angles.
Size: Plaques can vary in size, from small patches to large areas of pleural involvement.
Shape: Flat or slightly elevated fibrous deposits; may show irregular margins.
Position:
Most commonly located on the parietal pleura of the lateral chest wall, diaphragm, or mediastinal pleura.
Spares the visceral pleura.
May be associated with rounded atelectasis, a condition where adjacent lung tissue folds and collapses due to pleural fibrosis.
Character:
May appear as soft tissue density or show calcification (dense, well-defined plaques).
Time:
Slowly progressive and typically stable over time; calcification may develop years after exposure.
These findings reflect:
Asbestos exposure:
A marker of past asbestos exposure, typically presenting decades after initial contact.
Fibrotic response:
A benign reaction to asbestos fibers lodged in the pleura.
Prior hemothorax:
Fibrous reaction following blood accumulation in the pleural space, often due to trauma or surgery.
Smoking history and malignancy risk:
Smoking significantly increases the risk of developing lung cancer or mesothelioma in individuals with pleural plaques and a history of asbestos exposure.
Differential diagnosis:
Benign pleural thickening:
Post-inflammatory or post-traumatic pleural thickening.
Tuberculous pleuritis.
Calcified pleural plaques:
Asbestos exposure (most common).
Old infections (e.g., empyema or hemothorax with organized fibrosis).
Diffuse pleural thickening:
Differs from plaques by involving the visceral pleura and causing restrictive lung disease (often secondary to asbestos exposure or other inflammatory conditions).
Rounded atelectasis:
Focal lung collapse adjacent to pleural plaques or thickening, with characteristic findings on CT such as “comet-tail” signs.
Recommendations:
Obtain a detailed occupational and exposure history to assess asbestos exposure.
Assess smoking history and counsel on cessation to reduce the synergistic risk of malignancy.
Perform Chest CT for detailed evaluation of pleural plaques, especially if calcification or rounded atelectasis is suspected.
Monitor for associated asbestos-related diseases, such as asbestosis or mesothelioma, particularly in symptomatic patients.
Regular surveillance imaging may be warranted in high-risk individuals (e.g., smokers with plaques).
Key points and pearls:
Pleural plaques are not precursors to mesothelioma, but they indicate significant asbestos exposure, increasing the risk of other asbestos-related diseases.
Prior hemothorax can result in localized pleural thickening resembling plaques due to fibrotic healing.
Plaques typically spare the costophrenic angles and visceral pleura, helping differentiate them from other causes of pleural thickening.
Calcified plaques are easily recognized on imaging and may remain stable for years.
Smoking history and asbestos exposure together significantly raise the risk of lung cancer and mesothelioma, warranting close monitoring.
Rounded atelectasis is a potential complication, commonly found adjacent to pleural plaques and requiring recognition to avoid misdiagnosis as malignancy.
