Focal pleural thickening mimicking pleural plaques on chest computed tomography: tips and tricks

Our plain-English summary of Focal pleural thickening mimicking pleural plaques on chest computed tomography: tips and tricks, by K.M. Alfudhili, D.A. Lynch, F. Laurent, et al (The British Journal of Radiology, 2016).

The study

• Authors: K.M. Alfudhili, D.A. Lynch, F. Laurent, G.R. Ferretti, V. Dunet, C. Beigelman-Aubry
• Journal: The British Journal of Radiology
• Published: 2016;89(1057):20150792
• Type of article: Review
• Cited by: 19 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Diagnosis of pleural plaques (PPs) is commonly straightforward, especially when a typical appearance is observed in a context of previous asbestos exposure. Nevertheless, numerous causes of focal pleural thickening may be seen in routine practice. They may be related to normal structures, functional pleural thickening, previous tuberculosis, pleural metastasis, silicosis or other rarer conditions. An application of a rigorous technical approach as well as a familiarity with loco-regional anatomy and the knowledge of typical aspects of PP are required. Indeed, false-positive or false-negative results may engender psychological and medico-legal consequences or can delay diagnosis of malignant pleural involvement. Correct recognition of PPs is crucial, as they may also be an independent risk factor for mortality from lung cancer in asbestos-exposed workers particularly in either smokers or former/ex-smokers. Finally, the presence of PP(s) may help in considering asbestosis as a cause of interstitial lung disease predominating in the subpleural area of the lower lobes. The aim of this pictorial essay is to provide a brief reminder of the normal anatomy of the pleura and its surroundings as well as the various aspects of PPs. Afterwards, the common pitfalls encountered in PP diagnosis will be emphasized and practical clues to differentiate actual plaque and pseudoplaque will be concisely described.

In plain English

This article was a pictorial review by radiologists, not a study of patients. It explained how to tell asbestos-related pleural plaques from other focal thickening of the chest lining (the pleura) on CT scans. It showed individual cases in images but reported no study group or statistical analysis. The authors described the normal anatomy of the pleura and chest wall and the usual look of pleural plaques. They then went through things that can mimic plaques. These included normal chest muscles, temporary thickening at the back of the lungs, thickening of the inner pleural layer, old tuberculosis, silicosis, sarcoidosis, cancer spread to the pleura, and bone or fat structures. Their tips included checking for a smooth lung-chest wall border on the lung window setting and using three window settings. When thickening appeared at the back of the lungs on a scan taken lying on the back, they called for a face-down scan at no higher dose to see whether it reversed. The authors concluded that knowing the typical appearance and location of plaques is crucial for recognizing them correctly.

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: Pictorial review (educational essay with example CT images; no study group or statistical analysis)
• Who was studied: No study population. The article used illustrative chest CT images from individual cases, such as a 57-year-old female patient with cervical carcinoma. The number and source of cases are not stated.
• Exposure: Asbestos exposure, described generally as the cause of pleural plaques, mostly at work. No fiber types or doses are discussed.
• Main results:
  • Pleural plaques are calcified in 10%-15% of cases. The article cites this figure from another publication (its reference 4); it is not the authors' own data.
  • Normal muscles (transversus thoracis, subcostal, intercostal) can mimic plaques. A sharp and regular lung-chest wall interface on the lung window setting helps avoid false positive findings.
  • When thickening is seen at the back of the lungs on a scan with the patient lying on the back, the authors call for an additional scan lying face down. That scan should use a dose no higher than the first scan.
  • Such posterior thickening may be functional (temporary). The face-down scan confirms that it reverses in most cases.
  • Thickening of the visceral pleura, left over from earlier pleural effusion, is typically accompanied by crow's-feet, parenchymal bands or rounded atelectasis.
  • Old tuberculosis or fungal infection often causes pleural thickening near the tops of the lungs (apices).
  • Sarcoidosis can produce pseudoplaques from clusters of granulomas under the pleura. Silicosis should be considered when there are centrilobular or perilymphatic nodules.
  • Pleural metastasis (cancer spread to the pleura) should be suspected when the thickening has an atypical shape or location.
  • Osteophytes, bone tumours and opacified vessels should not be confused with real plaques. Thickening with the density of fat is usually extrapleural fat or a lipoma.
• The authors' conclusion: The authors concluded that knowing the typical appearance and location of pleural plaques is crucial for recognizing them correctly and telling them apart from other conditions.

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, Pleural Plaques, Asbestos Exposure, Metastasis, Silicosis, Lung Cancer, Interstitial Lung Disease, Pleura.

Related studies

• 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)
• 3-Dimensional Quantification of Composite Pleural Plaque Volume in Patients Exposed to Asbestos Using High-resolution Computed Tomography: A Validation Study — G. Dournes, A. Dubois, et al. (2019)
• The usefulness of computed tomography in detecting asbestos-related pleural abnormalities in people who had indeterminate chest radiographs: the Libby, MT, experience — O.I. Muravov, W.E. Kaye, et al. (2005)
• Computed tomography features in malignant pleural mesothelioma and other commonly seen pleural diseases — M. Metintas, I. Ucgun, et al. (2002)
• Focal dependent pleural thickening at MDCT: pleural lesion or functional abnormality? — M. Claude-Desroches, G. Bierry, et al. (2012)
• Findings from high resolution computed tomography of the lung and pleura of symptom free workers exposed to amosite who had normal chest radiographs and pulmonary function tests — S. Neri, A. Antonelli, et al. (1994)

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