Asbestos-Related Pleural Disease

General Considerations

• Salts of salicic acid
• 90% of asbestos in the USA is white asbestos (chrysotile) occurs in automotive workers, shipfitters, construction workers
• Asbestos particles invoke a hemorrhagic response in the lung
• Fibers are then coated with a ferritin-like material resulting in ferruginous bodies
• Produces its damage in respiratory bronchioles and alveoli
• Affects lower lobes first
• The presence of pulmonary parenchymal changes differentiates asbestosis from asbestos-related pleural disease

Imaging Findings

• Opacities are small and irregularly shaped
• Cardiac silhouette may become shaggy
• All patients with asbestos-related pleural disease have, by definition, some pleural involvement
• Pleural involvement without parenchymal disease is common
• Pleural plaque
• Parietal pleural plaques in the mid lung are the most common asbestos-related disorder and are usually bilateral
• They occur most often in the 6^th-9^th interspaces usually sparing the apices and lung bases and involve the parietal pleura
• Diffuse pleural thickening
• Less common than pleural plaques
• Diffuse pleural thickening involves diaphragmatic pleura, blunting of costophrenic sulci and lateral pleural thickening
• Pleural calcification
• Pleural calcification occurs in about 50% with asbestos-related disease, especially along the diaphragmatic pleura
• Calcified pleural plaques seen en face have a characteristic rolled edge along their margins, denser than in the central portion of the plaque
• The appearance of the entire plaque has been likened to a holly leaf
• Later manifestation of pleural disease, calcification may occur in plaque or diffuse pleural thickening (less often)
• Pleural effusion
• Effusion alone may occur early in the disease (first 20 years) in about 3% of cases
• Exudative, occasionally bloody, one-sided or bilateral
• In contrast to silicosis, hilar lymph nodes are rarely affected

Associations with lung cancer and mesothelioma

• Estimated to occur in 20-25% of those heavily exposed to asbestos
• Asbestos-related lung cancer is usually either squamous cell or adenocarcinoma
• Bronchogenic carcinoma is almost always associated with cigarette smoking
• Increases risk of bronchogenic carcinoma up to 100x over that in non-smoking, non-asbestos exposed population
• Mesotheliomas are not related to cigarette smoking
• Mesotheliomas most often due to crocidolite particles

 
Asbestos-Related Pleural Disease. There are innumerable pleural plaques, seen mostly en face. They have a typical appearance called a "rolled-edge" (red arrows. They have been likened to the appearance of a "holly leaf." There is also plaque-like, pleural calcification present (yellow arrows).

Asbestos-Related Pleural Disease. Again, there are innumerable pleural plaques, seen both en face (white arrows) and in profile (black arrows).