Reviewers: Elliot Weisenberg, M.D. (see Reviewers page)
Revised: 26 September 2011, last major update September 2011
Copyright: (c) 2003-2011, PathologyOutlines.com, Inc.
● Crystalline hydrated silicates that form fibers
● Causes localized fibrous plaques, pleural effusions, parenchymal interstitial fibrosis (asbestosis), bronchogenic carcinoma, mesothelioma, laryngeal carcinoma and possibly colon carcinoma
● Increased incidence of mesothelioma in families of asbestos workers
● Exists in serpentine/chrysotile (curly, flexible) and amphibole (straight, stiff, brittle) forms; most asbestos in industry are serpentine, but amphiboles are more pathogenic; link with mesothelioma is almost always with amphibole form
● Chrysotiles usually are caught in upper respiratory passages, removed by mucociliary elevator; they are soluble and leached from tissue if they reach alveoli
● Amphiboles (straight, stiff) go deeper into lungs; fibers > 8 mm and thinner than 0.5 mm are more injurious
● Both types are fibrogenic; act as tumor initiator and promoter; generate free radicals; toxic chemicals (tobacco smoke) may also be adsorbed to asbestos fibers
● Asbestos may act by countering antioxidant effect of Vitamin C (ascorbic acid) (Hum Pathol 2003;34:737)
● Relative risks compared to normal population: asbestos and bronchogenic carcinoma has RR of 5; with tobacco use, RR is 55
● Asbestos and mesothelioma (pleural, pericardial, peritoneal) has RR of 1000; no increased risk with smoking
● Incidence of mesothelioma expected to increase until 2020-2025 due to lag time between exposure and diagnosis
● Note: asbestos related tumors have no special histologic features
End of Lung-nontumor > Pneumoconiosis > Asbestos
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