Minimal pathologic changes of the lung and asbestos exposure

Our plain-English summary of Minimal pathologic changes of the lung and asbestos exposure, by D. Bellis, A. Andrion, L. Delsedime, et al (Human Pathology, 1989).

The study

• Authors: D. Bellis, A. Andrion, L. Delsedime, F. Mollo
• Journal: Human Pathology
• Published: 1989;20(2):102-6
• Cited by: 16 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000052).

Abstract

A group of 199 autopsy subjects was investigated for minimal pathologic pulmonary changes possibly resulting from asbestos exposure. According to the standards proposed by the Pneumoconiosis Committee of the College of American Pathologists, features consistent with asbestosis grade 1 (AG1) include findings of bilateral pleural plaques, high concentrations of asbestos bodies (ABs) in digested lung tissue, and a history of occupational risk. Similar changes without evidence of ABs on histologic section and referred to as small airway lesions (SALs) present a less well-correlated association. In this study, SALs showed significant differences when compared with the features observed in subjects without possible asbestos-related pulmonary fibrotic changes. Minimal bronchioloalveolar fibrotic changes with concomitant presence of ABs can be considered a mild pneumoconiotic lesion (AG1), and SALs may be regarded as an additional indicator of asbestos exposure.

In plain English

Lung slides from 199 people autopsied in Turin, Italy, from 1977 to 1984 were examined. The authors sought minimal scarring around the small airways. They called it asbestosis grade 1 (AG1) when at least two asbestos bodies were seen on the slides, one on the same slide as the scarring, and "small airway lesions" (SALs) when none were seen. SALs were found in 22 people, AG1 in 15, advanced asbestosis in 15, and no mineral dust-related lung changes in 147. In digested lung tissue, median asbestos bodies per gram of dry lung were 409 with SALs and 830 with AG1, and the SAL median was seven times that of people without changes. Possible or definite work exposure to asbestos was recorded for 12 of 22 SAL subjects, 13 of 15 AG1 subjects and 59 of 147 without changes. Bilateral pleural plaques differed significantly between people with and without these changes. The authors concluded that AG1 may be a distinct asbestos-induced lesion, and SALs an additional indicator of possible asbestos exposure. They noted the cases were highly selected for mineral fiber exposure, and AG1 progression was unproven.

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: Autopsy (pathology) study: retrospective review of stored lung tissue sections, with groups compared by chi square test
• Who was studied: 199 autopsy subjects (183 men, 16 women) from an autopsy population studied for asbestos-related disease at the University Hospital of Turin, Italy, 1977 to 1984. Groups were 22 with SALs, 15 with AG1, 15 with advanced asbestosis (excluded from the comparisons), and 147 without mineral dust-related pulmonary changes.
• Exposure: Asbestos exposure judged from occupational history (possible or definite professional exposure), asbestos bodies and uncoated mineral fibers counted per gram of dry lung in digested tissue, and the presence of pleural plaques. Fiber types were not specified. Some subjects also had rockwool or fiberglass exposure.
• Main results:
  • SALs were found in 22 of 199 subjects (11%), all men
  • Group totals in Table 1: 147 without mineral dust-related changes, 22 with SALs, 15 with AG1, 15 with advanced asbestosis, 199 in all
  • Asbestos bodies were present in digested lung tissue in 15 of 22 SAL subjects (68%), all of whom had more than 100 per gram of dry lung. All 15 AG1 cases (100%) had more than 100 per gram.
  • Median asbestos body count in digested lung tissue was 409 per gram in SAL cases and 830 per gram in AG1 cases
  • The authors state that the median asbestos body count in digested lung tissue of SAL subjects was seven times higher than in subjects without mineral dust-related pulmonary changes. The scanned text prints that group's median as '.56' per gram.
  • Pleural plaques (unilateral or bilateral) were found in 12 of 22 SAL subjects (55%), 9 of 15 AG1 subjects (60%) and 57 of 147 subjects without changes (39%)
  • Bilateral pleural plaques differed significantly between the groups with and without mineral dust-related pulmonary changes (P less than .001), but not between the SAL and AG1 groups
  • Possible or definite occupational asbestos exposure was found in 12 of 22 SAL subjects (55%) and 13 of 15 AG1 subjects (87%) (P greater than .05), and in 59 of 147 subjects without changes (40%)
  • For asbestos bodies in digested lung tissue and occupational status, the authors found no significant differences between SAL subjects and those without mineral dust-related pulmonary changes
  • The authors judged that AG1 features were significantly related to bilateral pleural plaques, high asbestos body concentrations and occupational asbestos history, compared with subjects without these changes, and considered it conceivable that AG1 is a distinct lesion induced by asbestos
  • Counting uncoated mineral fibers by light microscopy was found to be of dubious use and added no information
  • Smoking habits were uniformly distributed between subjects with and without mineral dust-related pulmonary changes
• The authors' conclusion: The authors concluded that SALs may be regarded as an additional indicator of possible asbestos exposure. They also concluded that when SALs are seen together with asbestos bodies on histologic sections, classifying them as AG1 (mild asbestosis) is justified from a pathologic view.
• Limitations the authors state:
  • The prevalence figures do not reflect the general autopsy population, because the cases were highly selected for mineral fiber exposure (84 of 184 subjects, 45.6%)
  • The number of slides examined may affect the chance of finding asbestos bodies, and therefore whether a case is classed as SAL or AG1
  • There is no definite evidence that AG1 progresses to overt interstitial fibrosis
  • A synergistic effect of smoking on the fibrotic lesions could not be excluded
  • Light microscopy misses many short fibers and cannot reliably tell asbestos from non-asbestos fibers

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Autopsy, Pneumoconiosis, Bilateral, Pleural Plaques, Asbestos Bodies.

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