Asbestos induced diffuse pleural fibrosis: pathology and mineralogy

Our plain-English summary of Asbestos induced diffuse pleural fibrosis: pathology and mineralogy, by M. Stephens, A.R. Gibbs, F.D. Pooley, et al (Thorax, 1987).

The study

• Authors: M. Stephens, A.R. Gibbs, F.D. Pooley, J.C. Wagner
• Journal: Thorax
• Published: 1987;42(8):583-8
• Cited by: 49 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000359).

Abstract

Lungs from seven cases of diffuse pleural fibrosis with known asbestos exposure were studied to determine the gross and microscopic pathological features and relate these to the analysed mineral fibre content of the lung. All seven individuals had had substantial exposure, ranging from two to 25 years, and chronic chest problems and at necropsy all cases met the criteria for compensatable disease. Macroscopically, all had extensive visceral pleural fibrosis and extensive areas of adhesions, and four also had discrete parietal pleural plaques. The histological features were similar in all the cases--most strikingly the basket weave pattern of the thickened pleura and a dense subpleural parenchymal interstitial fibrosis with fine honeycombing, extending up to 1 cm into the underlying lung. The similar histological appearances raise the possibility that diffuse pleural fibrosis and pleural plaques have a similar pathogenesis. Amphibole asbestos (crocidolite and amosite) counts were high in six of the seven cases and chrysotile counts in four; four cases had high mullite counts, but the importance of this is not known. It is concluded that diffuse pleural fibrosis is a specific asbestos associated entity, of uncertain pathogenesis, with mineral fibre counts falling between those found with plaques and those in minimal asbestosis.

In plain English

This study described the lungs of seven men with diffuse pleural fibrosis (widespread thickening of the lining around the lungs) and known asbestos exposure. The lungs were examined at necropsy from 1979 to 1986 and drawn from about 1200 asbestos-related necropsies. The men's exposure had lasted two to 25 years. All seven had extensive thickening of the visceral pleura, the layer covering the lung. Four also had parietal pleural plaques. Four were diagnosed only after death. Under the microscope all cases looked similar: a basket weave pattern in the thickened pleura, and dense scarring with fine honeycombing reaching no more than 1 cm into the lung. Amphibole (crocidolite and amosite) counts were high in six cases, from 2.4 to 28 million fibres per gram of dried lung. In the seventh case they were within the laboratory's normal range. Four cases had high chrysotile counts and four had high mullite counts. The authors said the importance of the mullite was unknown. The authors concluded that diffuse pleural fibrosis is a specific asbestos-associated entity whose mechanism of development is uncertain, with fibre counts between those seen with plaques and those in minimal asbestosis.

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: pathology and mineral fibre analysis of lungs taken at necropsy
• Who was studied: seven men with diffuse pleural fibrosis whose lungs were examined at necropsies from 1979 to 1986, drawn from about 1200 asbestos-related necropsies
• Exposure: substantial exposure to various types of asbestos lasting two to 25 years, in jobs including pipe fitter, engineer cutting asbestos sheets, maintenance fitter, caravan maker using blue asbestos, munitions factory worker and boilermaker
• Main results:
  • All seven cases had extensive visceral pleural fibrosis, most noticeable at the bases of the lungs.
  • Four of the seven cases also had parietal pleural plaques.
  • In four cases (cases 2, 3, 5 and 6) diffuse pleural fibrosis was diagnosed only after necropsy.
  • Two cases had a history of recurrent unexplained pleural effusions.
  • All cases showed a basket weave pattern of pleural fibrosis, and dense subpleural interstitial fibrosis with fine honeycombing that extended no more than 1 cm into the lung.
  • The grade of pulmonary interstitial fibrosis ranged from 1 to 3.
  • In none of the seven cases was asbestosis detected clinically or radiologically.
  • Amphibole (crocidolite and amosite) counts were high in six cases, ranging from 2.4 to 28 million fibres per gram of dried lung.
  • In case 6 the amphibole count was relatively low and within the laboratory's normal range (less than 1 million per gram of dried lung).
  • Chrysotile counts were high in four of the seven cases.
  • Four cases had high mullite counts; the authors did not know whether this was important.
  • Light microscopic fibre counts in these cases exceeded the laboratory's figures for non-exposed people (below 20,000 per gram) and for pleural plaques (10,000 to 50,000 per gram). They reached the levels seen in minimal to slight asbestosis.
• The authors' conclusion: The authors concluded that diffuse pleural fibrosis is a specific asbestos-associated entity. They found its mineral fibre counts fall between those found with plaques and those in minimal asbestosis. They said its pathogenesis, meaning how it develops, is uncertain.
• Limitations the authors state:
  • The diagnostic criteria used for compensatable diffuse pleural fibrosis were described as preliminary.
  • Lung cancer in three cases and severe pneumonia in three cases made it difficult to judge lung scarring by eye.
  • Only two cases had a known history of pleural effusions, but unnoticed episodes could have occurred in the others.

Topics

Medical terms in this study, explained in our Lexicon: Fibrosis, Pathology, Mineralogy, Asbestos Exposure, Autopsy, Pleural Plaques, Pleura, Interstitial Fibrosis.

Related studies

• Fibre distribution in the lungs and pleura of subjects with asbestos related diffuse pleural fibrosis — A.R. Gibbs, M. Stephens, et al. (1991)
• Asbestos-induced pleural fibrosis and impaired lung function — D.A. Schwartz, L.J. Fuortes, et al. (1990)
• Determinants of restrictive lung function in asbestos-induced pleural fibrosis — D.A. Schwartz, J.R. Galvin, et al. (1990)
• Determinants of restrictive lung function in asbestos-induced pleural fibrosis — C.J. Bergin (1991)
• Chronic pleuritic pain in four patients with asbestos induced pleural fibrosis — A. Miller (1990)
• Asbestos-induced pleural fibrosis and impaired exercise physiology — J.F. Shih, J.S. Wilson, et al. (1994)

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