Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans

Our plain-English summary of Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans, by D.A. Lynch, G. Gamsu, C.S. Ray, et al (Radiology, 1988).

The study

• Authors: D.A. Lynch, G. Gamsu, C.S. Ray, D.R. Aberle
• Journal: Radiology
• Published: 1988;169(3):603-7
• Cited by: 77 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. 000920).

Abstract

In 260 asbestos-exposed individuals evaluated by means of computed tomography (CT), 43 unsuspected pulmonary masses were found in 27 individuals. The masses included fissural pleural plaques (n = 10), dense fibrotic bands (n = 3), round atelectasis (n = 11), carcinomas (n = 3), and other presumed benign masses (n = 16). The most helpful features in the diagnosis of rounded atelectasis with CT were (a) contiguity to areas of diffuse pleural thickening, (b) a lentiform or wedge-shaped outline, (c) evidence of volume loss in the adjacent lung, and (d) a characteristic "comet tail" of vessels and bronchi sweeping into the margins of the mass. Less advanced areas of focal atelectasis had fewer classic features. Intrafissural pleural plaques were readily identified with high-resolution CT. In asbestos-related masses, the demonstration of stability over time is necessary. Careful interpretation of CT and high-resolution CT features and close surveillance can obviate the need for biopsy in the majority of instances.

In plain English

This study described focal lung masses seen on CT scans of 260 people with occupational asbestos exposure in shipyard or construction work. They had been referred for CT because two certified B readers disagreed about whether they had asbestosis or asbestos-related pleural disease. The scans included conventional CT and high-resolution CT (HRCT). Twenty-seven people had 43 previously unsuspected masses: 10 plaques inside the lung fissures, 3 dense fibrotic bands, 11 areas of rounded atelectasis, 3 carcinomas, and 16 other presumed benign masses. Masses were judged benign mainly when they stayed unchanged on repeat imaging. HRCT showed the location of the fissural plaques in every case, while 4 of these 10 plaques looked like lung nodules on conventional CT. The three carcinomas were all round or nodular. In contrast, 15 of 18 benign pleural-based masses were lens- or wedge-shaped. The authors concluded that stability on imaging for 2 years or more was the best sign that a mass was benign, and that all other cases deserved rigorous follow-up.

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 review of CT and high-resolution CT scans in a referred group of asbestos-exposed people (case series). Masses were judged benign on the basis of unchanged serial chest radiographs or CT scans over an average of 2 years (range 9 months to 4 years).
• Who was studied: 260 asbestos-exposed individuals referred for CT because two certified B readers disagreed about the presence of asbestosis or asbestos-related pleural disease. Mean age was 63 years and all but four were male. People referred specifically for lung masses were excluded. The authors were at the University of California, San Francisco and Brookside Hospital, San Pablo, California. Study dates are not given.
• Exposure: Occupational asbestos exposure in shipyard or construction work, with at least 10 years since first exposure. Fiber types and doses are not stated.
• Main results:
  • Of the 260 individuals, 27 had 43 focal mass lesions.
  • The 43 masses were fissural pleural plaques (10), dense fibrotic bands (3), round atelectasis (11), carcinomas (3) and other presumed benign masses (16).
  • Only three of the 43 masses were malignant.
  • In the whole study population, 170 (65%) had focal pleural plaques on CT and 44 (17%) had diffuse pleural thickening.
  • In the whole study population, 49% had HRCT changes indicating moderate to high probability of asbestosis.
  • Four of the 10 fissural plaques appeared as lung nodules on conventional CT. With HRCT, the fissure was identified in all cases.
  • With HRCT, the fissure was clearly seen as a thin line in all cases, so the plaque's location inside the fissure could be established.
  • The 11 rounded atelectasis masses occurred in 8 patients, and in all 8 patients the masses were stable for at least 9 months.
  • The 3 carcinomas were all round or nodular, whereas 15 of 18 benign pleural masses were lentiform or wedge-shaped.
• The authors' conclusion: The authors concluded that radiographic stability for 2 years or more is the best index of benignity and that all other cases deserve rigorous follow-up. They also wrote that a lentiform or wedge-shaped outline, a comet tail, lobar volume loss and contiguity with diffuse pleural thickening strongly favor benignity.
• Limitations the authors state:
  • Nodule densitometry, which the authors describe as part of the usual evaluation of small nodules, was not performed.
  • The indeterminate and presumed benign nodules had been stable for up to 2 years, and the authors said repeat imaging would still be necessary.

Topics

Medical terms in this study, explained in our Lexicon: High-Resolution CT (HRCT), Pleural Plaques, Atelectasis, Carcinoma, Rounded Atelectasis, Diffuse Pleural Thickening, Bronchus, Biopsy.

Related studies

• Conventional and high resolution computed tomography in the diagnosis of asbestos-related diseases — D.A. Lynch, G. Gamsu, et al. (1989)
• Asbestos-related pleural and parenchymal fibrosis: detection with high-resolution CT — D.R. Aberle, G. Gamsu, et al. (1988)
• High-resolution CT of benign asbestos-related diseases: clinical and radiographic correlation — D.R. Aberle, G. Gamsu, et al. (1988)
• High-resolution computed tomography of asbestos-related diseases — D.R. Aberle (1991)
• Specificity of high-resolution CT findings in pulmonary asbestosis: do patients scanned for other indications have similar findings? — C.J. Bergin, R.A. Castellino, et al. (1994)
• Why is high resolution computerized tomography scanning used in evaluating the lungs? — W.A. Graves, J.D. Collins, et al. (1989)

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