|Print Date:||May 18, 2013, 10:10 pm|
|Text||Prolonged exposure to asbestos can result in a variety of pleural and pulmonary disorders. Benign pleural disease is the most common manifestation and includes pleural plaques, pleural effusions, and diffuse pleural fibrosis. Malignant asbestos related disease occurs as malignant mesothelioma.
Pleural plaques do not produce any symptoms and are incidentally discovered as focal irregular areas of pleural thickening that involve the parietal pleura. They consist of dense bands of collagen and are not considered premalignant. They are usually bilateral and symmetric and predominate in the lower half of the thorax. Diffuse pleural thickening is not seen as often. It is manifested by a uniform homogeneous density with smooth contours and often after a residual of a previous asbestos effusion.
Benign asbestos pleural effusions are exudative pleural reactions after asbestos exposure and often occur within 10 years of exposure. Approximately 50% of these patients will have residual diffuse pleural thickening with blunting of the costophrenic angles after the effusion resolves.
Pleural calcifications are a later manifestation of asbestos exposure. The calcifications occur within the pleural plaques and are often seen 30 to 40 years after the onset of exposure. CT is typically needed to distinguish calcified pleural plaques from underlying pulmonary nodules.
Diffuse interstitial fibrosis (also known as asbestosis) is the most significant change that occurs in the lung secondary to asbestos exposure. There is a dose-effect relationship for workers exposed to high dust concentrations for prolonged periods of time. Symptoms include dyspnea and dry cough and progressive reduction of vital capacity and diffusing capacity. The parenchymal fibrosis begins around the respiratory bronchioles in the lower lobes adjacent to the visceral pleura. The fibrosis may progress to honeycombing with complete destruction of the alveolar architecture.
Benign parenchymal lesions include rounded atelectasis, benign fibrotic masses, and transpulmonary bands. Malignant neoplasms associated with asbestos exposure include bronchogenic carcinoma, which develops in 20-25% of heavily exposed asbestos workers. There is an even higher incidence if they are smokers. Malignant mesothelioma is an uncommon neoplasm of the pleural cavity and peritoneum, It is highly associated with asbestos exposure and the risk of developing mesothelioma in an asbestos worker is as high as 10% over their lifetime.
|Contributor||William A Mercanti (National Capital Consortium)|
|Peer Reviewer||David S. Feigin, M.D. (Johns Hopkins Hospitals)|
|Record Number||: 4480|
|Location:||Chest, Pulmonary (ex. Heart)|
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