Mesotheliomatous tumors in South Africa: pathology and experimental pathology

Our plain-English summary of Mesotheliomatous tumors in South Africa: pathology and experimental pathology, by I. Webster (Annals of the New York Academy of Sciences, 1965).

The study

• Author: I. Webster
• Journal: Annals of the New York Academy of Sciences
• Published: 1965;132(1):623-46
• Cited by: 29 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. 002514).

Summary of the article

This article reviewed the pathology of mesotheliomatous tumors in South Africa and the evidence linking them with asbestos. Of 169 primary mesotheliomas diagnosed in South Africa, 125 had been examined at the Pneumoconiosis Research Unit, Johannesburg. The description of malignant tumors was based mainly on 41 cases confirmed at post-mortem. The tumors varied in cell type and often had a dense collagen stroma. In 16 autopsy cases a primary multicentric bronchiolar carcinoma could not be excluded. Hyaluronic acid in the tumor or pleural fluid was judged a useful guide but not an absolute diagnostic criterion. Pleural biopsy and exfoliative cytology results were also reported. Specimens from a Northern Cape tuberculosis hospital showed a significantly higher incidence of mesotheliomatous tumors than those from a Southern Transvaal hospital. Of 41 cases examinable for asbestosis, 9 showed none, although 6 of these had some connection with the Northern Cape. In 350 Miners' Medical Bureau records from asbestos areas, malignancy was increased in cases with asbestosis, but mesothelioma was not more common with marked than with slight asbestosis. No mesothelioma was found in people exposed to Transvaal blue asbestos or amosite. In animals, 6 of 177 inoculated intrapleurally with crocidolite developed mesotheliomatous tumors, but such tumors also occurred occasionally after chrysotile, silica and carbon. The author concluded that these tumors appeared related to asbestos inhalation, particularly crocidolite, but that other factors could not yet be excluded.

PubMed has no abstract for this study, and the article doesn't print one. We wrote this summary from the full article with the help of AI. It is not the authors' wording.

In plain English

This 1965 report described the author's pathology work on mesotheliomatous tumors in South Africa, where 169 primary mesothelioma cases had been diagnosed. The tumor descriptions rested mainly on 41 post-mortem-confirmed cases. In 16 pleural cases, a primary bronchiolar carcinoma could not be ruled out. Of the 41 cases with enough material, 9 showed no asbestosis; 6 of these had some link to the Northern Cape. Specimens from a Northern Cape tuberculosis hospital showed mesotheliomatous tumors significantly more often than a Southern Transvaal hospital's. In 350 autopsy records from asbestos areas, results suggested more malignancy with marked than slight asbestosis, but not more mesothelioma. No pleural mesothelioma had been found among people exposed to Transvaal blue asbestos. Of 177 animals inoculated with crocidolite, 6 developed mesotheliomatous tumors; such tumors also occasionally followed chrysotile, silica or carbon. The author concluded that the tumors appeared related to inhaled asbestos, particularly crocidolite, but other factors could not yet be excluded. Only 7 of the 125 cases seen at the Pneumoconiosis Research Unit had a full post-mortem there or at the University of the Witwatersrand.

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: Descriptive pathology report on a case series of mesotheliomatous tumors, with analyses of autopsy records, and a brief account of animal experiments
• Who was studied: 169 cases of primary mesothelioma diagnosed in South Africa, of which 125 were examined at the Pneumoconiosis Research Unit, Johannesburg. Tumor pathology was based mainly on 41 post-mortem-confirmed cases. A separate analysis covered 350 Miners' Medical Bureau autopsy records from the asbestos areas. Laboratory animals were also studied.
• Exposure: Asbestos dust in the Northern Cape, including occupational and atmospheric exposure. Comparisons were made with Transvaal blue asbestos, amosite and manganese dust. Animals were exposed to crocidolite, chrysotile, silica and carbon.
• Main results:
  • In 16 cases diagnosed at autopsy as pleural mesothelioma, a primary multicentric bronchiolar carcinoma could not be excluded.
  • Of the 41 cases with enough material to diagnose asbestosis, 9 showed no evidence of asbestosis.
  • Of the 9 mesothelioma patients without asbestosis, 6 were associated in some way with the Northern Cape.
  • Specimens from two State Tuberculosis Hospitals were compared, one in the Northern Cape and one in the Southern Transvaal. The percentage of tuberculosis was similar at both, but the author reported a significantly higher incidence of mesotheliomatous tumors in the Northern Cape specimens.
  • In the 350 autopsy records, the results suggested more malignancy in cases with marked asbestosis than in those with slight asbestosis. According to the author, this did not apply to mesothelioma.
  • No case of pleural mesothelioma had been found in people exposed to Transvaal blue asbestos dust.
  • Among people who had worked with amosite asbestos, 2 of 9 Whites and 4 of 60 Bantu died of carcinoma of the lung. The author described this as higher than expected in South Africa.
  • Of 177 animals inoculated intrapleurally with crocidolite asbestos, 6 developed mesotheliomatous tumors. Such tumors were also found occasionally in animals inoculated with chrysotile, silica and carbon.
  • Some guinea pigs exposed to a high concentration of asbestos dust developed multicentric bronchiolar carcinomas. The tumors appeared in those given the greater number of exposures.
• The authors' conclusion: The author concluded that these peripheral tumors appeared related to inhaling asbestos, particularly crocidolite. However, there were enough points against this that the situation should be reviewed continually, and other possible factors could not yet be excluded.
• Limitations the authors state:
  • Of the 125 cases examined at the Pneumoconiosis Research Unit, only 7 had a full post-mortem at that unit or at the University of the Witwatersrand. Most cases described as confirmed at post-mortem were assessed from selected specimens sent by hospitals that had no pathologist on staff.
  • The ages recorded in the 350 autopsy records may not always be accurate.
  • The final diagnosis was unknown for a relatively large percentage of the cases examined by pleural fluid cytology.
  • The amosite lung cancer findings rested on a small number of cases.
  • The exact classification of these peripheral tumors is difficult.
  • Hyaluronic acid in the tumor or in pleural fluid is a useful guide but not an absolute diagnostic criterion.

Topics

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

Medical terms in this study, explained in our Lexicon: Pathology, Mesothelioma, Pneumoconiosis, Collagen, Autopsy, Carcinoma, Hyaluronic Acid, Pleural Biopsy.

Related studies

• Radiological and pathological correlations in asbestosis in the Republic of South Africa and the United Kingdom. II. A preliminary study of observer variation in the classification of radiographs of asbestos-exposed workers and the relation of pathology and x-ray appearances — A. Caplan, J.C. Gilson, et al. (1965)
• Asbestosis in non-experimental animals in South Africa — I. Webster (1963)
• Characterization of asbestos fibers in lungs and mesotheliomatous tissues of baboons following long-term inhalation — K. Hiroshima, Y. Murai, et al. (1993)
• Asbestosis in South Africa--certain geographical and environmental considerations — G.K. Sluis-Cremer (1965)
• Radiological and pathological correlations in asbestosis in the Republic of South Africa and the United Kingdom. I. A proposed radiological classification of asbestosis — G.K. Sluis-Cremer, C.P. Theron (1965)
• Risk of asbestosis in crocidolite and amosite mines in South Africa — L.M. Irwig, R.S. du Toit, et al. (1979)

Browse more research in Annals of the New York Academy of Sciences, or return to medical research.