Lung
Pneumoconiosis
Asbestosis


Topic Completed: 1 September 2011

Minor changes: 20 August 2020

Copyright: 2003-2020, PathologyOutlines.com, Inc.

PubMed search: asbestosis [title] pneumoconiosis pulmonary

Elliot Weisenberg, M.D.
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Cite this page: Weisenberg E. Asbestosis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/lungnontumorasbestosis.html. Accessed September 29th, 2020.
Definition / general
  • Similar to other pneumoconiosis
  • Initial injury is at bifurcations of small airways and ducts; macrophages ingest fibers, release chemotactic factors and fibrogenic mediators, causing interstitial fibrosis similar to other fibrosing lung diseases such as UIP
  • Begins around respiratory bronchioles and alveolar ducts, extends distally; eventually causes honeycomb lungs
  • Begins in lower lobes and subpleurally (in contrast to coal workers' pneumoconiosisP and silicosis), progresses to middle and upper lobes
  • Visceral pleura becomes fibrotic, may bind lung to chest wall; may have associated Caplan syndrome
  • Symptoms: usually begin after 10 years of exposure, initially shortness of breath with exertion and later at rest; may progress to heart failure
  • Pleural plaques: well circumscribed plaques of dense collagen, often with calcium; on parietal pleura and dome of diaphragm; do not contain asbestos bodies, but rare if no asbestos history; may induce pleural effusions, usually no symptoms
  • Asbestos fiber detection: H&E, Prussian blue, incineration and EM
Asbestos
  • 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
Gross images

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Pleural plaque

Pleural plaque

Microscopic (histologic) description
  • Early: interstitial pneumonia with desquamative features, hyperplastic alveolar cells with intracytoplasmic Mallory's hyaline tissue
  • Later: diffuse interstitial fibrosis with honeycombing (silicosis is nodular), asbestos bodies (golden brown, fusiform or beaded rods with translucent center; asbestos fibers coated with iron-containing proteinaceous material); iron from phagocyte ferritin
  • Asbestos fibers may have oxalate crystal deposition (Hum Pathol 2003;34:737)
  • Ferruginous bodies: inorganic particulates coated with phagocyte ferritin
Microscopic (histologic) images

Contributed by Jijgee Munkhdelger, M.D., Ph.D. and Andrey Bychkov, M.D., Ph.D.
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Asbestos bodies in alveolar spaces

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Ferruginous body

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Asbestos body

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Dumbbell shaped asbestos body

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