Clinical consequences of asbestos-related diffuse pleural thickening: A review

Our plain-English summary of Clinical consequences of asbestos-related diffuse pleural thickening: A review, by S.E. Miles, A. Sandrini, A.R. Johnson, et al (Journal of Occupational Medicine and Toxicology, 2008).

The study

• Authors: S.E. Miles, A. Sandrini, A.R. Johnson, D.H. Yates
• Journal: Journal of Occupational Medicine and Toxicology
• Published: 2008;3:20
• Cited by: 30 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Asbestos-related diffuse pleural thickening (DPT), or extensive fibrosis of the visceral pleura secondary to asbestos exposure, is increasingly common due to the large number of workers previously exposed to asbestos. It may coexist with asbestos related pleural plaques but has a distinctly different pathology. The pathogenesis of this condition as distinct from pleural plaques is gradually becoming understood. Generation of reactive oxygen and nitrogen species, profibrotic cytokines and growth factors in response to asbestos is likely to play a role in the formation of a fibrinous intrapleural matrix. Benign asbestos related pleural effusions commonly antedate the development of diffuse pleural thickening. Environmental as well as occupational exposure to asbestos may also result in pleural fibrosis, particularly in geographic areas with naturally occurring asbestiform soil minerals. Pleural disorders may also occur after household exposure. High resolution computed tomography (CT) is more sensitive and specific than chest radiography for the diagnosis of diffuse pleural thickening, and several classification systems for asbestos-related disorders have been devised. Magnetic resonance imaging and fluorodeoxyglucose positron emission tomography (PET) scanning may be useful in distinguishing between DPT and malignant mesothelioma. DPT may be associated with symptoms such as dyspnoea and chest pain. It causes a restrictive defect on lung function and may rarely result in respiratory failure and death. Treatment is primarily supportive.

In plain English

This article was a narrative review, written for clinicians, of asbestos-related diffuse pleural thickening (DPT), scarring of the lining covering the lung. It reported no new data and described DPT as distinct from pleural plaques. Drawing on other studies, the authors reported that DPT occurred in 5 to 13.5% of asbestos workers 3 to 34 years after first exposure, and that benign asbestos-related pleural effusions often came before it. Surveillance figures they cited from New South Wales, Australia, recorded 120 new DPT cases in 2006, probably an underestimate. They wrote that DPT may cause breathlessness and has been associated with chest pain, usually mild, and in very rare cases with respiratory failure and death. They described a restrictive pattern on lung function tests, and said DPT is usually only mildly symptomatic. They reported that high resolution CT is more sensitive and specific than chest X-ray for diagnosis, and that MRI and PET may help distinguish DPT from malignant mesothelioma. Treatment was described as mainly supportive. The authors concluded that DPT is probably under-recognised, that its incidence is rising, and that more research is needed on its natural history, imaging and treatment.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative review aimed at clinicians; no original data and no stated literature search method
• Who was studied: No study population; the review summarised published studies and surveillance data on asbestos-related diffuse pleural thickening, mainly in asbestos-exposed workers, with some environmental and household exposure
• Exposure: Asbestos exposure in general (occupational, environmental and household); the review stated that DPT can follow exposure to all types of asbestos and is thought to be dose-related
• Main results:
  • Citing prospective studies of asbestos workers, the review reported DPT in 5 to 13.5% of workers 3 to 34 years after first asbestos contact
  • The review reported that the Dust Diseases Board of New South Wales recorded an increase in DPT cases from 65 in 2002 to 133 in 2006
  • Citing the SABRE NSW surveillance scheme, the review reported 120 new DPT cases, 143 mesothelioma cases and 240 cases of pleural plaques alone notified in 2006, and noted these were likely underestimates
  • The review reported that pleural effusions before the development of DPT had been reported in between 31.4% and 37% of cases
  • The review described DPT as usually bilateral, with about one third of cases unilateral
  • The review stated that DPT may cause exertional breathlessness and has been associated with chest pain and, in very rare cases, with respiratory failure and death
  • The review stated that chronic chest pain may be a feature of DPT but is usually mild
  • The review described a restrictive defect on lung function in DPT, which may occur independently of asbestosis
  • In one cited study of a selected series of compensated patients with moderate to severe DPT, 95.5% complained of breathlessness
  • The review stated that high resolution CT is more sensitive and specific than chest radiography for diagnosing DPT
  • The review stated that MRI and FDG-PET may be useful in distinguishing malignant from benign pleural disease
  • The review described treatment as supportive and symptomatic, with non-invasive ventilation for respiratory failure
• The authors' conclusion: The authors concluded that DPT is a recognised consequence of asbestos exposure and benign asbestos-related pleural effusions but is probably under-recognised. They stated it is usually only mildly symptomatic, that its incidence is rising, that total numbers are likely to exceed those of malignant mesothelioma in the future, and that further research is needed on its natural history, radiology and treatment.
• Limitations the authors state:
  • The authors stated that the prevalence of DPT is difficult to document because it causes no symptoms in its earliest stages
  • The authors stated that no reliable figures exist on the share of DPT caused by asbestos versus other causes, and that asbestos-related DPT is a diagnosis of exclusion
  • The authors stated that few studies have examined the natural history of DPT
  • The authors stated that the link between CT findings and symptoms has not been well investigated
  • The authors stated that few data exist on the best management of patients with DPT

Topics

Medical terms in this study, explained in our Lexicon: Diffuse Pleural Thickening, Fibrosis, Visceral Pleura, Asbestos Exposure, Pleural Plaques, Pathology, Cytokine, Pleural Effusion.

Related studies

• Asbestos-related lesions of the pleura: parietal plaques compared to diffuse thickening studied with chest roentgenography, computed tomography, lung function, and gas exchange — G. Hillerdal, P. Malmberg, et al. (1990)
• Asbestos-related pleural diseases: dimensional criteria are not appropriate to differentiate diffuse pleural thickening from pleural plaques — J. Ameille, M. Matrat, et al. (2004)
• Diffuse thickening superimposed on circumscribed pleural thickening related to asbestos exposure — A. Miller, J.A. Miller (1993)
• Asbestos-related diffuse pleural thickening — N. Fujimoto, K. Kato, et al. (2014)
• Diffuse pleural thickening following heart failure-related pleural effusions in an asbestos exposed patient — M. Evison, P. Barber (2015)
• Yellow Nail Syndrome with Bilateral Pleural Plaques and Diffuse Pleural Thickening: A Mimic of Asbestos Related Disease — A. Dallmann, R.L. Attanoos (2018)

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