· 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
o Fibers are then coated with a ferritin-like material resulting in ferruginous bodies
o 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
o Opacities are small and irregularly shaped
o Cardiac silhouette may become shaggy
· Imaging findings
o 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 6th-9th 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
o 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 calcification, asbestos exposure. White arrow points to a calcified pleural plaque of asbestos-related pleural disease seen en face. The overall appearance of the plaque has been likened to a holly leaf and the dense white edge of the plaque is called a rolled edge. The black arrows point to many of the calcified pleural plaques seen in profile.
For a larger photo of the same image without arrows, click here
§ 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
o In contrast to silicosis, hilar lymph nodes are rarely affected
· Associations with lung cancer and mesothelioma
o Estimated to occur in 20-25% of those heavily exposed to asbestos
o Asbestos-related lung cancer is usually either squamous cell or adenocarcinoma
o 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
o Mesotheliomas are not related to cigarette smoking
§ Mesotheliomas most often due to crocidolite particles
