The role of analytical SEM in the determination of causation in malignant mesothelioma

Our plain-English summary of The role of analytical SEM in the determination of causation in malignant mesothelioma, by V.L. Roggli (Ultrastructural Pathology, 2006).

The study

• Author: V.L. Roggli
• Journal: Ultrastructural Pathology
• Published: 2006;30(1):31-5
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The causative relationship between asbestos exposure and mesothelioma is firmly established. Some information in this regard comes from analysis of the fiber content of lung tissue by means of analytical electron microscopy. The author has had the opportunity to study the lung asbestos content of 396 cases of mesothelioma, including 28 peritoneal cases, by means of analytical scanning electron microscopy. The highest fiber levels occurred in patients who also had asbestosis, which was found in 12% of pleural and 43% of peritoneal cases. Elevated tissue asbestos content was identified in 87% of pleural and 75% of peritoneal cases. Peritoneal cases that are asbestos related have on average a higher lung fiber burden than pleural cases. Mesotheliomas in women have elevated tissue asbestos content in about 60% of cases, and many of these had a history of exposure as a household contact of an asbestos worker. The main fiber type identified in our series was amphibole, predominantly amosite. These fibers have been demonstrated to reach the target tissue, the pleura.

In plain English

This article was a short overview by the author of 24 years of laboratory experience measuring asbestos in lung tissue from people with malignant mesothelioma. It also described the laboratory methods and discussed other published studies. The author had analyzed lung tissue from 396 patients: 368 with pleural and 28 with peritoneal mesothelioma. Among pleural cases, the median asbestos body count was 12,400 per gram in those who also had asbestosis, 845 in those with pleural plaques only, and 105 in those with neither. About 87% of pleural cases had elevated fiber content and, in the author's words, appeared related to prior asbestos exposure. In 13% the content could not be told apart from background levels. Peritoneal cases with asbestosis had a median of 132,000 asbestos bodies per gram, while those with neither plaques nor asbestosis had 3.9. Among 48 women, about 40% had asbestos content indistinguishable from background. The author reported that about 64% of pleural mesotheliomas in women appeared asbestos related, mostly through household contact with an asbestos worker. The author noted that results can differ strikingly between laboratories.

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 overview of the author's own laboratory case series (lung tissue fiber analysis by light microscopy and analytical scanning electron microscopy), combined with a description of methods and discussion of other published studies
• Who was studied: 396 patients with malignant mesothelioma whose lung tissue the author analyzed over about 24 years: 368 pleural cases and 28 peritoneal cases, including 48 women. The article does not say where the patients came from.
• Exposure: Asbestos content of lung tissue: asbestos bodies counted by light microscopy, and uncoated fibers counted and typed (amosite, crocidolite, tremolite, chrysotile and others) by scanning electron microscopy with energy dispersive X-ray analysis
• Main results:
  • Pleural mesothelioma cases: the median asbestos body count was 12,400 per gram with asbestosis (44 cases), 845 per gram with parietal pleural plaques but no asbestosis (113 cases), and 105 per gram with neither (207 cases)
  • Pleural cases: asbestos body content was within the laboratory's normal range (0 to 20 per gram) in 74 cases (20%). In 27 of these 74, fiber content was elevated by electron microscopy.
  • Pleural cases: asbestos content was indistinguishable from background in 13%, and approximately 87% had elevated fiber content
  • Peritoneal cases: the median asbestos body count was 132,000 per gram with asbestosis (12 cases), compared with 12,400 per gram for pleural cases with asbestosis
  • Peritoneal cases with plaques only had a median of 350 asbestos bodies per gram (versus 845 for pleural cases with plaques only)
  • Peritoneal cases with neither plaques nor asbestosis (11 cases) had a median asbestos body count of only 3.9 per gram
  • Women (48 cases): the median asbestos body count was 15.5 per gram. 27 had counts in the background range, and 8 of these had elevated fiber counts by electron microscopy, so about 40% had content indistinguishable from background.
  • Approximately 64% of pleural mesotheliomas in women appeared asbestos related, most from exposure as a household contact of an asbestos worker. The majority of peritoneal mesotheliomas in women were not related to asbestos.
  • Most cases with a normal-range asbestos body count but elevated fiber content by electron microscopy had mainly noncommercial amphiboles, mostly tremolite
  • From an earlier cited study of 94 United States cases by Roggli and colleagues (not this series): 58% of more than 1500 fibers analyzed were amosite and 3% were crocidolite
• The authors' conclusion: The author concluded that approximately 87% of the pleural mesotheliomas analyzed appear to be related to prior asbestos exposure. The author also stated that the peritoneal findings are consistent with the observation that, on average, more asbestos exposure is needed for peritoneal than for pleural mesothelioma.
• Limitations the authors state:
  • Results can differ strikingly between laboratories even for the same sample, so comparisons between laboratories need caution
  • Fiber content varies from site to site within the lung. Paired samples usually agree within a factor of 2 or 3 but rarely differ by a factor of 10 or more.
  • Most fiber burden studies, including lung analyses, examined lung parenchyma rather than the pleura itself
  • Some asbestos bodies and fibers may be lost during preparation, and the smallest fibers are hard to count reproducibly

Topics

The National Library of Medicine indexes this study under subjects our site covers: Amosite, Mesothelioma, Peritoneal mesothelioma.

Medical terms in this study, explained in our Lexicon: Causation, Malignant Mesothelioma, Asbestos Exposure, Mesothelioma, Scanning Electron Microscopy (SEM), Fiber Burden, Amphibole Group, Amosite.

Related studies

• Malignant mesothelioma not related to asbestos exposure: Analytical scanning electron microscopic analysis of 83 cases and comparison with 442 asbestos-related cases — A. Kraynie, G.G. de Ridder, et al. (2016)
• Asbestos fiber type in malignant mesothelioma: an analytical scanning electron microscopic study of 94 cases — V.L. Roggli, P.C. Pratt, et al. (1993)
• A technical comparison of evaluating asbestos concentration by phase-contrast microscopy (PCM), scanning electron microscopy (SEM), and analytical transmission electron microscopy (ATEM) as illustrated from data generated from a case report — R.F. Dodson, S.P. Hammar, et al. (2008)
• Comments on Dodson et al., A technical comparison of evaluating asbestos concentration by phase contrast microscopy (PCM), scanning electron microscopy (SEM), and analytical transmission electron microscopy (ATEM) as illustrated from data generated from a case report — V.L. Roggli, T.A. Sporn, et al. (2008)
• The Significance of Short Latency in Mesothelioma for Attribution of Causation: Report of a Case with Predisposing Germline Mutations and Review of the Literature — S. Klebe, A.J. Hocking, et al. (2021)
• Comparison of the results of asbestos fibre dust counts in lung tissue obtained by analytical electron microscopy and light microscopy — F.D. Pooley, D.L. Ranson (1986)

Browse more research in Ultrastructural Pathology, or return to medical research.