Focal dependent pleural thickening at MDCT: pleural lesion or functional abnormality?

Our plain-English summary of Focal dependent pleural thickening at MDCT: pleural lesion or functional abnormality?, by M. Claude-Desroches, G. Bierry, D. Touitou-Gottenberg, et al (Diagnostic and Interventional Imaging, 2012).

The study

• Authors: M. Claude-Desroches, G. Bierry, D. Touitou-Gottenberg, J.L. Golmard, P.A. Grenier, C. Beigelman-Aubry
• Journal: Diagnostic and Interventional Imaging
• Published: 2012;93(5):360-4
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: To describe the characteristics of reversible focal pleural thickenings (PTs) mimicking real plaques, that firstly suggest asbestos exposure or pleural metastasis; to propose an imaging strategy and propose an explanation for their mechanism of formation.

Patients And Methods: Retrospective review of data from 19 patients with PTs fitting the description of pleural plaques at chest computed tomography (CT) and presenting modifications (clearance or appearance) of at least one PT at an additional chest examination in prone position.

Results: A total of 152 PTs were recorded on the first chest CT examinations with a range of two to 19 pleural opacities per patient. All PTs had a posterior distribution in the lower lobes. On the additional acquisitions, 144 PTs disappeared. Seventeen patients presented complete regression of PTs and two patients presented persistence of eight PTs.

Conclusion: Additional low dose acquisition in prone position should be performed in all patients presenting with focal PT in a dependent and basal location. This may allow to exclude a pleural plaque in case of asbestos exposure but also a pleural metastasis in oncologic patients. These reversible dependent PTs could be related to physiological focal accumulation of lymphatic fluid in subpleural area.

Copyright © 2012 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

In plain English

This was a retrospective study by radiologists of 19 patients (12 women, seven men). Their routine chest CT scans, taken lying on the back, showed non-calcified patches of pleural thickening in the lower back part of the chest that resembled asbestos-related pleural plaques. Patients were identified between January 2005 and May 2007. Three had prior asbestos exposure and three had a history of malignancies. Each also had an ultra-low-dose scan lying face down (prone). The first scans showed 152 thickenings, 44 of which met criteria for typical pleural plaques. On the prone scans, 144 disappeared (95%). Seventeen patients had complete disappearance, and eight thickenings persisted in two patients. Five new thickenings appeared in five patients. Of the three asbestos-exposed patients, two had complete disappearance and one had three persistent indeterminate thickenings. The authors concluded that an extra low-dose prone scan should be performed in all patients with focal pleural thickening in this dependent, basal (lower back) location. They suggested, without tissue confirmation, that these thickenings are probably related to normal lymphatic drainage. They noted the small number of patients.

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: Retrospective review of CT scans (supine scan compared with an additional prone scan)
• Who was studied: 19 patients (12 females, seven males) scanned for various reasons between January 2005 and May 2007. All had non-calcified focal pleural thickenings resembling asbestos-related pleural plaques, located only in dependent (lower back) areas.
• Exposure: Not a study of asbestos exposure as such. Three of the 19 patients had prior asbestos exposure. No fiber types, jobs or doses are given. The comparison was between supine CT and an additional ultra-low-dose prone CT.
• Main results:
  • On the first (supine) scans, 152 pleural thickenings were recorded in the 19 patients: 44 typical of pleural plaques and 108 indeterminate.
  • Patients had from two to 19 thickenings each (mean 8.3).
  • On the prone scans, 144 of the initial thickenings (43 typical and 101 indeterminate) disappeared (95%, p less than 0.001).
  • Eight initial thickenings (one typical, seven indeterminate) persisted in two patients. The other 17 patients had complete regression.
  • Five new indeterminate thickenings appeared on the prone scans, in five patients.
  • Of the three patients with prior asbestos exposure, two had complete regression and one had three persistent indeterminate thickenings.
  • In the asbestos-exposed patients, the four typical pleural plaques seen on the first scan were not seen on the second.
  • All three patients with a history of malignancies showed complete regression of the thickenings.
  • The mean size of the persistent thickenings fell from 6.9 to 5.8 mm. This change was not statistically significant (p = 0.3).
• The authors' conclusion: The authors concluded that an additional low-dose prone CT acquisition should be performed in all patients with focal pleural thickening in a dependent and basal location. They considered the reversible nature of these thickenings probably related to normal lymphatic drainage.
• Limitations the authors state:
  • Small cohort, especially the small number (6) of patients with prior asbestos exposure or a history of malignancies.
  • No tissue (histopathological) confirmation of the hypothesis that the reversible thickenings come from normal pleural fluid accumulation.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Thickening, Asbestos Exposure, Metastasis, Pleural Plaques.

Related studies

• Focal pleural thickening mimicking pleural plaques on chest computed tomography: tips and tricks — K.M. Alfudhili, D.A. Lynch, et al. (2016)
• Asbestos-related lesions of the pleura: parietal plaques compared to diffuse thickening studied with chest roentgenography, computed tomography, lung function, and gas exchange — G. Hillerdal, P. Malmberg, et al. (1990)
• Focal pleural tumorlike conditions: nodules and masses beyond mesotheliomas and metastasis — M.C. de Paula, D.L. Escuissato, et al. (2015)
• Asbestos-related focal lung masses: manifestations on conventional and high-resolution CT scans — D.A. Lynch, G. Gamsu, et al. (1988)
• Asbestos-related pleural diseases: dimensional criteria are not appropriate to differentiate diffuse pleural thickening from pleural plaques — J. Ameille, M. Matrat, et al. (2004)
• Asbestos-related diffuse pleural thickening — N. Fujimoto, K. Kato, et al. (2014)

Browse return to medical research.