Hyaline and calcified pleural plaques as an index of exposure to asbestos

Our plain-English summary of Hyaline and calcified pleural plaques as an index of exposure to asbestos, by D.O. Hourihane, L. Lessof, P.C. Richardson (British Medical Journal, 1966).

The study

• Authors: D.O. Hourihane, L. Lessof, P.C. Richardson
• Journal: British Medical Journal
• Published: 1966;1(5495):1069-74
• Cited by: 134 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. 004707).

Abstract

A close association between exposure to asbestos and the development of pleural plaques has been shown. A cause-and-effect relationship is probable. The most extensive lesions are radiologically detectable, and the disease asbestosis is then also present, despite the absence of any other radiological abnormality. The sources of asbestos are considered and evidence is presented to suggest that there is a widespread non-industrial community exposure. Mesotheliomata are common in patients with pleural plaques, and it is suggested that there is a dose-response relationship between the asbestos and the development of these neoplasms. The question of a relationship between lung cancer and asbestos is left open, but the value of radiological surveys for pleural plaques is emphasized in any study of this problem. Asbestos is not the sole cause of pleural plaques, but it is certainly the most common.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This 1966 paper from the London Hospital described 100 people with pleural plaques. Of these, 56 were found at necropsy (post-mortem examination) and 50 on chest x-rays, with six in both groups. In 1964, plaques were found in 16 of 381 necropsies, which the authors called a minimal figure. Asbestos bodies were found in the lungs of all 56 necropsy cases with plaques, compared with 28 of 115 (24.3%) routine necropsies. Only seven of the 51 necropsy cases with x-rays had shown calcification in life. Among 36 people with calcified plaques found on routine x-rays, 83% reported asbestos exposure, compared with 11% of 36 matched controls, a statistically significant difference. Exposures included factory work, lagging, handling asbestos cargoes and living near an asbestos factory. Mesothelioma was found in 15 of the 56 necropsy cases (27%). The authors concluded that plaques can be taken as evidence of asbestos exposure and that cause and effect is probable. They left the question of lung cancer open, saying their groups were too small to assess it.

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 people with pleural plaques found at necropsy and on chest x-rays, with comparisons against routine necropsy lungs and a matched control group of patients with normal x-rays
• Who was studied: 100 people with pleural plaques at the London Hospital and its Bernhard Baron Institute of Pathology, 1964 to 1965: 56 found at necropsy and 50 found on x-ray, with 6 overlapping. The x-ray group was 33 males and 17 females aged 41 to 81.
• Exposure: Asbestos in general; the article does not name fiber types. Exposures recorded included work at an asbestos factory, insulators and laggers, dockers or lorry-drivers handling asbestos cargoes, relatives working with asbestos, and living within half a mile of an asbestos factory.
• Main results:
  • During 1964, 16 cases with plaques were found among 381 necropsies (at least 4.2%).
  • Asbestos bodies were found in the lungs of all 56 necropsy cases with plaques, compared with 28 of 115 (24.3%) routine necropsies. The authors reported this difference as statistically significant (P less than 0.01).
  • Among the 36 people with pleural calcification found at routine x-ray sessions (people with known asbestosis or mesothelioma excluded), 83% gave a history of asbestos exposure, compared with 11% of 36 matched controls (P less than 0.01).
  • In the whole x-ray series of 50, a history of asbestos exposure was obtained in 43 (86%).
  • Of the 51 necropsy plaque cases with x-rays available, only seven had shown pleural calcification in life, and all seven had histological asbestosis at necropsy.
  • Among the 56 necropsy plaque cases, 15 (27%) had mesothelioma (10 peritoneal, 5 pleural). After excluding people with classical or histological asbestosis, 3 of 32 (9%) had mesothelioma, all pleural.
  • Of people with plaques not visible on x-ray, 1 of 21 (5%) had lived within half a mile of a large asbestos factory. This compared with 10 of 30 (30%) in the x-ray-positive series and 3% of controls.
  • Tissue from 12 plaque cases was incinerated, and asbestos fibres were found in four of them.
• The authors' conclusion: The authors concluded that the link between asbestos and pleural plaques is close enough that plaques can be taken as evidence of asbestos exposure, and that cause and effect is probable. They suggested widespread non-industrial community exposure, proposed a dose-response relationship with mesothelioma, and left the lung cancer question open.
• Limitations the authors state:
  • The necropsy prevalence is a minimum, because many necropsies were not personally examined and plaques are easy to overlook.
  • Routine chest x-rays were not systematically searched for pleural calcification.
  • Most plaques seen at necropsy were not visible on chest x-rays.
  • The groups were too small to give evidence about lung cancer.
  • The effects of living near the factory could not easily be separated from casual work there or contact with relatives' clothes.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Dose-response relationship, Neoplasm, Lung Cancer.

Related studies

• 'Black Spots' and hyaline pleural plaques on the parietal pleura of 150 urban necropsy cases — K. Mitchev, P. Dumortier, et al. (2002)
• Subpleural fat pads in patients exposed to asbestos: distinction from non-calcified pleural plaques — E.N. Sargent, W.D. Boswell, et al. (1984)
• Calcified interlobar pleural plaques: visceral pleural involvement due to asbestos — E.N. Sargent, J.S. Felton, et al. (1981)
• Calcified plaques on mediastinal pleural reflections associated with asbestos dust exposure: four case reports — A. Solomon, G.K. Sluis-Cremer, et al. (1984)
• Calcified plaque in the superior portion of the major fissure. An unusual manifestation of asbestos exposure — S.B. Rupp, H. Jolles (1989)
• Multilocular peritoneal inclusion cyst (multicystic mesothelioma) with hyaline globules — J. Lamovec, J. Sinkovec (1996)

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