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asbestosis

Etiology: 1) exposure to asbestos fibers (see asbestos) 2) early massive exposure produces severe disease 3) tobacco smoke greatly increases the risk of asbestos- related cancer 4) all types of asbestos fibers have been implicated Epidemiology: - construction, automotive servicing, ship-building & mining industries are most commonly affected [3] Pathology: 1) pleural disease, multiple forms a) pleural plaques/fibrosis (hyalinosis simplex) - most common manifestation - generally represents exposure 20 years earlier - not precancerous - bilateral & symmetric - occurs along path of ribs - tends to progress & calcify b) pleural/diaphragmatic calcification c) thickened pleura (hyalinosis complicata) - uncommon complication - progressive calcification involves both visceral pleura & parietal pleura, lung apices & pericardium - recurrent acute inflammatory phase associated withfever & exudative pleural effusion d) pleural effusion (earliest complication) - always exudative - bloody in 70& - unilateral or bilateral - malignant mesothelioma must be excluded as a cause e) mesothelioma - pleural & peritoneal - constant gnawing chest pain - prolonged exposure is necessary - interval between exposure & mesothelioma is 30-40 years - no correlation with smoking 2) lung disease a) pulmonary fibrosis (long-term heavy exposure) - fibrosis of visceral pleura also occurs - progressive fibrosis & honeycombing may lead to cor pulmonale - clinically similar to idiopathic pulmonary fibrosis - affects primarily lower lobes of lung b) rounded atelectasis c) lung cancer - generally bronchial adenocarcinoma - interval between exposure & cancer is 15-35 years - accounts for most asbestos-related deaths - lower lobes affected twice as frequently as upper lobes - tumors are generally peripheral & frequently involve the pleura - also small cell carcinoma in smokers [3] - smoking & asbestos exposure synergistically increase risk of lung cancer to 60 fold relative to non-smokers without asbestos exposure [3] 3) other - pericardial tumor - peritoneal tumors - vocal cord polyps - increased incidence of lymphoma - laryngeal cancer - gastrointestinal cancer Clinical manifestations: 1) latent period of 10-15 years (20-30 years [3]) 2) symptoms a) gnawing chest pain or dull ache (43%) b) dyspnea (27%) c) cough (19%) d) weight loss (13) e) fever (7%) f) pleuritic chest pain is rare 3) signs a) pleural effusion may be present b) clubbing of the fingers (< 5%) c) bibasilar crackles d) pleuropericardial rub 4) see pathology Laboratory: 1) rheumatoid factor may be positive 2) anti-nuclear antibody (ANA) may be positive 3) pleural biopsy for mesothelioma 4) asbestois in specimen - asbestos in air - asbestos in water Radiology: 1) chest X-ray a) predominantly lower lobe infiltrates b) bilateral basilar reticulonodular infiltrates, 'shaggy heart sign' 2) high-resolution computed tomography (HRCT) a) pleural plaques or thickening (90%) 1] bilateral 2] latency of 10-20 years b) thickened intralobular & interlobular line (confirmation on prone image needed) c) parenchymal bands, often contiguous with pleura d) interstitial fibrosis with basilar predominance e) honeycombing (advanced disease) f) subpleural densities 1] curvilinear subpleural lines of variable length 2] often parallel to pleura 3] confirmation on prone image needed g) nodular pleural thickening suggests mesothelioma Differential diagnosis: (diaphragmatic calcification) 1) ankylosing spondylitis 2) old tuberculous pleurisy Complications: - cigarette smoking & asbestos have a synergistic effect on risk of lung cancer Management: - preventive medicine a) Pneumovax at diagnosis & 5 years later b) annual influenza vaccine

Related

asbestos mesothelioma

General

occupational lung disease

References

  1. Contribution from Peter Baylor, VA Medical Center, UCSF Fresno
  2. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 757-58
  3. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, 16, 17, 18, American College of Physicians, Philadelphia 1998, 2006, 2009, 2012, 2015, 2018.
  4. Paris C, Thierry S, Brochard P et al Pleural plaques and asbestosis: dose- and time-response relationships based on HRCT data. Eur Respir J. 2009 Jul;34(1):72-9 PMID: 19129281
  5. Markowitz SB, Levin SM, Miller A, Morabia A. Asbestos, asbestosis, smoking, and lung cancer. New findings from the North American insulator cohort. Am J Respir Crit Care Med. 2013 Jul 1;188(1):90-6. PMID: 23590275
  6. Stayner L, Welch LS, Lemen R. The worldwide pandemic of asbestos-related diseases. Annu Rev Public Health. 2013;34:205-16. Review. PMID: 23297667
  7. Fishwick D, Barber CM. Non-malignant asbestos-related diseases: a clinical view. Clin Med (Lond). 2014 Feb;14(1):68-71. PMID: 24532750 Free PMC Article
  8. National Heart, Lung, and Blood Institute (NHLBI) Asbestos-Related Lung Diseases https://www.nhlbi.nih.gov/health-topics/asbestos-related-lung-diseases