Diffuse thickening superimposed on circumscribed pleural thickening related to asbestos exposure

Our plain-English summary of Diffuse thickening superimposed on circumscribed pleural thickening related to asbestos exposure, by A. Miller, J.A. Miller (American Journal of Industrial Medicine, 1993).

The study

• Authors: A. Miller, J.A. Miller
• Journal: American Journal of Industrial Medicine
• Published: 1993;23(6):859-71
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Circumscribed and diffuse pleural thickening (PT), the most common radiographic manifestations of asbestos-related disease, have different pathogeneses, differential diagnostic criteria, and effects on pulmonary function. The important distinction between the two disorders is demonstrated by six patients in whom typical circumscribed PT was followed by diffuse PT in the same hemithorax. The diffuse PT came on 18-47 (mean 32.3) years after first exposure to asbestos. In four patients, clinically evident pleural effusions preceded the diffuse PT; the latter left all with moderate to severe restrictive ventilatory impairment. Patients with stable pleural plaques are at risk for diffuse PT and consequent greater ventilatory impairment, even though they are many years from first exposure to asbestos.

In plain English

This case series described six patients from one author's private practice whose serial chest X-rays showed diffuse pleural thickening developing over earlier pleural plaques on the same side. Five had worked in various trades at two United States Naval shipyards, one only during World War II. The four employed afterward had apparently worked there 15 to 23 years. The sixth was a powerhouse pipe fitter for 28 years. The article did not say which fiber types these patients were exposed to. Diffuse thickening appeared 18 to 47 years (mean 32.3) after exposure began. Four had clinically evident pleurisy with effusion 19 to 48 years after first exposure. Diffuse thickening became two-sided in four patients and right-sided only in two. Those four had moderate to severe restrictive lung impairment, with forced vital capacity 48 to 64% of predicted. Of the other two, one had normal lung function. The other, who had long-standing chronic obstructive lung disease, had combined obstructive-restrictive impairment. The authors concluded that people with long-standing, clinically inconsequential pleural plaques remain at risk for diffuse thickening and its associated lung function impairment.

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: case series of six patients, based on review of serial chest radiographs and pulmonary function tests
• Who was studied: six patients referred to one of the authors (A.M.) at a private office for clinical evaluation of asbestos-related disease. They were not part of the large asbestos-exposed populations surveyed at Mount Sinai. Five were former shipyard workers at two United States Naval shipyards and one was a powerhouse pipe fitter.
• Exposure: Occupational asbestos exposure in various trades at two United States Naval shipyards. One shipyard worker was employed only during World War II and the others after it. The article gives employment durations of 15 to 23 years right after referring to 'these four'. The sixth patient worked as a pipe fitter at a powerhouse from 1953 to 1981 (28 years). The fiber types these patients were exposed to were not specified.
• Main results:
  • In all six patients, diffuse pleural thickening appeared 18 to 47 years (mean 32.3 years) after the onset of occupational asbestos exposure.
  • Four of the six patients had clinically evident pleurisy with effusion 19 to 48 years after first exposure to asbestos.
  • On the films just before the diffuse thickening, four patients showed extensive plaques and two showed small plaques.
  • On the final film, diffuse thickening was present on both sides in four patients and on one side (the right in both) in two patients.
  • The four patients with diffuse thickening on both sides had moderate to severe restrictive impairment: forced vital capacity (FVC) 48 to 64% of predicted and functional residual capacity (FRC) 58 to 69% of predicted.
  • Of the two patients with one-sided diffuse thickening, patient B had normal lung function. Patient D, with a long history of chronic obstructive lung disease, had combined obstructive-restrictive impairment with FVC 45% of predicted.
  • Restrictive impairment remained after surgical removal of the thickened pleura (decortication) on one side in one patient and on both sides in another.
  • Signs of lung tissue scarring on X-ray were scored 0/0 in five patients and 1/0 in patient A on that patient's last film in 1986.
• The authors' conclusion: The authors concluded that patients with long-standing, clinically inconsequential pleural plaques remain at risk for diffuse pleural thickening and its associated impairment of lung function. They said this matters for surveillance.
• Limitations the authors state:
  • The authors said they had seen many other cases with both plaques and diffuse thickening on the same side. These were not reported because there were no serial films or other observations showing which came first.
  • The authors did not try to show plaques developing on top of existing diffuse thickening, because the plaques would be obscured.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Pleural Thickening, Asbestos Exposure, Diffuse Pleural Thickening, Hemithorax, Pleural Effusion, Pleural Plaques.

Related studies

• Increased body mass index is related to apparent circumscribed pleural thickening on plain chest radiographs — Y.C. Lee, C.K. Runnion, et al. (2001)
• 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)
• 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)
• Causes of pulmonary impairment in asbestos-exposed individuals with diffuse pleural thickening — S.T. Kee, G. Gamsu, et al. (1996)

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