Pleural irregularities and mediastinal pleural involvement in early stages of malignant pleural mesothelioma and benign asbestos pleural effusion

Our plain-English summary of Pleural irregularities and mediastinal pleural involvement in early stages of malignant pleural mesothelioma and benign asbestos pleural effusion, by K. Kato, K. Gemba, N. Fujimoto, et al (European Journal of Radiology, 2016).

The study

• Authors: K. Kato, K. Gemba, N. Fujimoto, K. Aoe, Y. Takeshima, K. Inai, T. Kishimoto
• Journal: European Journal of Radiology
• Published: 2016;85(9):1594-600
• Cited by: 14 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To elucidate differences in the level and localization of pleural irregularities in early malignant pleural mesothelioma (eMPM) and benign asbestos pleural effusion (BAPE) using CT.

Study Design: Retrospective assessment of CT findings of consecutive patients with BAPE at a single centre and patients with eMPM reported in Japanese vital statistics.

Methodology: Thirty-six patients with confirmed diagnoses of BAPE and sixty-six patients with confirmed diagnoses of eMPM (mesothelioma stages T1 or T2) were included. Informed consent, CT scans, and clinical and pathologic details were obtained for all patients and were reviewed by one radiologist, two pathologists, and two pulmonologists. Asbestosis, pleural plaque, rounded atelectasis, and diffuse pleural thickening were assessed in all patients.

Results: Prevalence of asbestosis, pleural plaque, rounded atelectasis, and diffuse pleural thickening was significantly higher in the BAPE group. Low-level irregularity was more common in the BAPE group (p<0.001), whereas high-level irregularity, mediastinal localization, and interlobar fissure were more prevalent in the eMPM group (p<0.001). Interlobar pleural irregularity was not observed in any patients in the BAPE group, although 55% of patients in the eMPM group showed interlobar pleural irregularity. Mediastinal pleural involvement was observed in 74% of patients in the eMPM group and had a positive predictive value of 89%.

Conclusion: This study demonstrates that the level and localization of plural irregularities significantly differed between patients with BAPE and eMPM. Large-scale prospective studies are needed to fully establish the diagnostic utility of such differences.

Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

In plain English

This retrospective study compared chest CT scans from two groups in Japan. The first was 36 men with benign asbestos pleural effusion (BAPE), meaning fluid around the lung linked to asbestos but not cancer, seen at Okayama Rosai Hospital from 2005 to 2008. The second was 66 patients with early-stage (T1 or T2) malignant pleural mesothelioma, drawn from mesothelioma deaths in Japanese Vital Statistics for 2003 to 2005. Reviewers graded how irregular the pleura (lung lining) looked and where the irregularity was. Pleural plaques were seen in 92% of the BAPE group and 35% of the mesothelioma group. Pleural effusion was common in both groups, with no significant difference. High-level irregularity or a mass was seen in 5.5% of the BAPE group and 36.4% of the mesothelioma group. Irregularity of the mediastinal pleura, the lining facing the centre of the chest, appeared in 74% of mesothelioma patients and 22% of BAPE patients. The authors concluded that the level and location of irregularities could help tell the two conditions apart, and they called for large prospective studies.

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 comparison of CT findings between a single-centre group of consecutive benign asbestos pleural effusion patients and a multicentre group of early malignant pleural mesothelioma patients identified through Japanese vital statistics
• Who was studied: Two groups, 102 patients in total. The BAPE group was 36 patients, all male, mean age 72.0, referred to Okayama Rosai Hospital between 1 March 2005 and 30 April 2008. The early mesothelioma group was 66 patients (56 male, 10 female), mean age 67.8, with stage T1 or T2 malignant pleural mesothelioma, selected from mesothelioma death cases in the Japanese Vital Statistics for 2003 to 2005.
• Exposure: Asbestos exposure; no fiber types, products or jobs were specified. All BAPE patients had a history of asbestos exposure, with mean exposure history 28.1 years and mean latency 46.3 years. In the mesothelioma group, 60.6% had occupational asbestos exposure, with mean exposure duration 16.6 years and mean latency 24.0 years.
• Main results:
  • Pleural plaque was seen in 33 of 36 (92%) BAPE patients and 23 of 66 (35%) early mesothelioma patients (p less than 0.001). Asbestosis was seen in 6 (17%) and 1 (2%) respectively (p less than 0.05).
  • Rounded atelectasis was found in 16 (44%) BAPE patients and 0 (0%) early mesothelioma patients. Diffuse pleural thickening was found in 9 (25%) and 1 (2%) respectively. Both differences had p less than 0.001.
  • Pleural effusion was found in 36 (100%) BAPE patients and 64 (97%) early mesothelioma patients (p = 0.291), a difference that was not statistically significant.
  • No or low-level pleural irregularity together was found in 94.4% of BAPE patients and 63.6% of early mesothelioma patients. High-level irregularity and mass formation together were found in 5.5% and 36.4% respectively (p less than 0.001). Mass formation was seen in no BAPE patients and in 9 (14%) mesothelioma patients.
  • Mediastinal pleural involvement was seen in 49 (74%) early mesothelioma patients and 8 (22%) BAPE patients (p less than 0.001). For early mesothelioma diagnosis it had a reported sensitivity of 79.5%, specificity of 81%, positive predictive value of 89% and negative predictive value of 68%.
  • Interlobar fissure irregularity was found in 36 (55%) early mesothelioma patients and in no BAPE patients (p less than 0.001). Basal irregularity was reported in 32 (91%) BAPE patients and 51 (77%) mesothelioma patients (p = 0.150), a difference that was not statistically significant.
  • On follow-up CT, pleural irregularities in BAPE patients regressed or stayed the same, while in early mesothelioma patients they worsened or stayed the same. One BAPE patient's high-level irregularity persisted over 5 years of follow-up.
• The authors' conclusion: The authors concluded that the level and location of pleural irregularities could potentially help distinguish benign asbestos pleural effusion from early malignant pleural mesothelioma. Pleural effusion did not differ between the groups, mediastinal pleural involvement was more frequent in early mesothelioma, and large multicentre prospective studies with long-term follow-up are needed.
• Limitations the authors state:
  • Because the mesothelioma group's data were collected retrospectively from multiple centres, CT scan parameters and protocols varied.
  • The BAPE group came from a single centre and may represent only one region of Japan.
  • The effect of contrast media on pleural irregularities could not be examined in all cases; only 8 cases (3 BAPE, 5 mesothelioma) had scans both with and without contrast.
  • CT findings were decided by team consensus, and inter-rater reliability and independent associations between parameters were not assessed.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Benign Asbestos Pleural Effusion, Mesothelioma, Informed Consent, CT Scan, Pleural Plaques, Rounded Atelectasis, Diffuse Pleural Thickening.

Related studies

• Clinical Investigation of Benign Asbestos Pleural Effusion — N. Fujimoto, K. Gemba, et al. (2015)
• Paraplegia due to massive asbestos-related pleural and mediastinal fibrosis — C.J. O'Brien, A.J. Franks (1987)
• A retrospective study on radiological findings of diffuse pleural thickening with benign asbestos pleural effusion in Japanese cases — T. Kishimoto, K. Kato, et al. (2022)
• Fatal pleural mesothelioma in Japan (2003-2008): evaluation of computed tomography findings — K. Kato, K. Gemba, et al. (2016)
• Symptomatic benign pleural effusions among asbestos insulation workers: residual radiographic abnormalities — R. Lilis, Y. Lerman, et al. (1988)
• Pleurectomy decortication in the treatment of the "trapped lung" in benign and malignant pleural effusions — S. Rathinam, D.A. Waller (2013)

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