Pleural plaques: a signpost of asbestos dust inhalation

Our plain-English summary of Pleural plaques: a signpost of asbestos dust inhalation, by E.N. Sargent, G. Jacobson, J.S. Gordonson (Seminars in Roentgenology, 1977).

The study

• Authors: E.N. Sargent, G. Jacobson, J.S. Gordonson
• Journal: Seminars in Roentgenology
• Published: 1977;12(4):287-97
• Cited by: 30 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. 002252).

Summary of the article

This review by three radiologists at the LAC-USC Medical Center, Los Angeles, described pleural plaques as a marker of asbestos dust inhalation. It reported no new study of patients. The authors noted that asbestos was used in more than 3000 commercial items and that disease often appeared 20 years or more after exposure began. They summarized published evidence linking plaques to occupational and nonoccupational exposure and described a proposed theory of how inhaled fibres reach the parietal pleura. They also described the gross and microscopic pathology of plaques. Most of the article covered radiographic appearances. Plaques were usually 1-5 mm thick, most often lay next to the 5th to 8th ribs, and spared the apices and costophrenic angles. Less than 25% of patients with plaques had interstitial lung disease. Calcification was found histologically in about 87% of plaques but was relatively uncommon on radiographs. The authors recommended oblique views and fluoroscopy, explained how to tell plaques from normal muscle and fat shadows, and reviewed other causes of pleural thickening and calcification. They cited a study in which bronchial carcinoma was 2½ times more frequent in men with plaques. They concluded that bilateral plaques should be considered caused by asbestos until proven otherwise, that a lifetime occupational history should be taken, and that such patients should have lifetime surveillance.

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 1977 article by three radiologists at the LAC-USC Medical Center in Los Angeles was a narrative review illustrated with radiographs, not a report of a new patient series. It outlined a proposed theory of how pleural plaques form, noting that no fully satisfactory explanation existed, and described how plaques look at autopsy, under the microscope and on X-rays. Drawing on earlier work, the authors wrote that asbestos dust inhalation is the most common, though not the only, cause of plaques. They added that all varieties of asbestos have been implicated, with the highest rate of association for anthophyllite. They described plaques as lying almost exclusively on the parietal pleura and usually on both sides. Plaques without calcium were often missed on routine X-rays until thick enough to show. The authors recommended oblique views and explained how to tell plaques from normal shadows and from other causes of thickening. Citing an earlier autopsy study, they noted calcification under the microscope in about 87% of plaques. The authors concluded that bilateral pleural plaques should be considered caused by asbestos dust inhalation until proven otherwise, and that such patients should have lifetime surveillance.

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 review and teaching article on the pathology and radiographic appearance of pleural plaques, illustrated with patient radiographs; not a report of a new patient series
• Who was studied: No defined study population. The article reviews published studies and shows illustrative radiographs, including one patient's films from 1967 to 1976. Several figures are cited to the authors' own study, listed as in press. The authors were radiologists at LAC-USC Medical Center, Los Angeles.
• Exposure: Asbestos dust inhalation, occupational and nonoccupational. Citing earlier work, the authors stated that all varieties of asbestos have been implicated, with the highest rate of association for anthophyllite.
• Main results:
  • The authors stated that no fully satisfactory explanation of plaque formation had been developed, and they presented a proposed theory: fibers move toward the lung periphery and reach the parietal pleura.
  • The authors described plaques as almost exclusively on the parietal pleura. They wrote that plaques are practically never found at the lung apices, below the 11th rib, in the costophrenic angles, or anteriorly near the costal cartilages.
  • Noncalcified plaques are not seen on radiographs until the fibrous tissue is thick enough, so they often go undetected and their prevalence during life is underestimated.
  • Plaque thickness was described as ranging from 1 mm to more than 10 mm, usually 1-5 mm. Plaques are usually bilateral, often symmetric, and most commonly lie next to the 5th to 8th ribs.
  • The authors strongly recommended oblique views. These confirm suspected plaques and detect additional plaques or thickening not seen on the standard front (PA) view.
  • Pleural calcification usually occurs 20 years or more after asbestos exposure and is relatively uncommon on radiographs. Citing an earlier autopsy study, the authors reported it is much more common under the microscope, in about 87% of plaques.
  • Citing an earlier study (Edge, a British shipbuilding population), the authors reported that bronchial carcinoma was more frequent in men with pleural plaques. This is not a finding of this article. The multiplier is garbled in the scan; it is printed as '2Yz times', apparently 2 and a half times.
  • The authors described pleural calcification after hemorrhage or infection as usually one-sided and often extensive and sheetlike, in contrast to asbestos-related plaques.
• The authors' conclusion: The authors concluded that bilateral pleural plaques are signposts of pleural asbestosis. They wrote that such plaques should be considered caused by asbestos dust inhalation until proven otherwise, with a careful lifetime occupational history taken. They also stated that patients with bilateral plaques should have lifetime surveillance.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Plaques, Parietal Pleura, Pathology, Apices, Costophrenic angle, Interstitial Lung Disease, Pleural Thickening, Carcinoma.

Related studies

• Calcified plaques on mediastinal pleural reflections associated with asbestos dust exposure: four case reports — A. Solomon, G.K. Sluis-Cremer, et al. (1984)
• Multiple pleural plaques. II — H.C. Anton (1968)
• Calcified interlobar pleural plaques: visceral pleural involvement due to asbestos — E.N. Sargent, J.S. Felton, et al. (1981)
• Calcified plaque in the superior portion of the major fissure. An unusual manifestation of asbestos exposure — S.B. Rupp, H. Jolles (1989)
• Bilateral pleural thickening: a manifestation of asbestos dust exposure — E.N. Sargent, J. Gordonson, et al. (1978)
• Pleural fibrocalcific plaques and asbestos exposure — L.O. Meurman (1968)

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