Interobserver Agreement in Histopathological Subtyping of Malignant Pleural Mesotheliomas

Our plain-English summary of Interobserver Agreement in Histopathological Subtyping of Malignant Pleural Mesotheliomas, by M. Mlika, F. Mezni (Türk Patoloji Dergisi, 2021).

The study

• Authors: M. Mlika, F. Mezni
• Journal: Türk Patoloji Dergisi
• Published: 2021;37(1):56-62
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: Many recent studies are pointing out the heterogeneity between pathologists in the classification of malignant pleural mesotheliomas. Besides, they reported the prognostic impact of classifying epithelioid mesotheliomas according to the predominant architectural features and the nuclear grade. The authors assessed the interobserver and the intraobserver agreement of subtyping mesotheliomas between 2 pathologists used to thoracic pathology.

Material And Method: The observers reviewed all the slides of the malignant pleural mesotheliomas diagnosed during the period ranging from 2004 to 2017. The Cohen Kappa was performed in order to evaluate the agreement between both observers into classifying mesotheliomas, subtyping and grading epithelioid mesotheliomas. Two rounds of examination were planned with a delay period of one month. After the first round, the reviewers discussed the different difficulties and challenges they faced. All the statistic tests were performed using the SPSS software version 12.0.

Results: After the first round, a fair agreement between both observers was reported. After the second round, an improvement of the concordance rate with a good agreement in subtyping epithelioid mesotheliomas was noticed. Concerning the grading of mesotheliomas, the interobserver agreement was poor even after the second round examination. The intraobserver reproducibility of epithelioid mesothelioma subtyping was fair or moderate for both reviewers. The intraobserver agreement was poor concerning the grading of epithelioid mesothelioma.

Conclusion: Integrating subtyping and grading of epithelioid mesotheliomas into a new classification necessitates an important training of the pathologists. The architectural features' definitions have to be clarified in order to avoid using own subjective opinions and habits by pathologists.

In plain English

This study looked at how consistently two pathologists experienced in chest (thoracic) pathology classified malignant pleural mesothelioma under the microscope. It did not study asbestos exposure. The pathologists reviewed slides of 50 malignant pleural mesotheliomas diagnosed at one institution from 2004 to 2017: 44 epithelioid, 4 sarcomatoid and 2 biphasic. They sorted the epithelioid tumours into patterns of growth (subtypes) and into grades. They did this twice, one month apart, and met between rounds to discuss the difficulties they had found. Agreement was measured with a statistic called kappa. In the first round, the two pathologists' agreement on subtype was fair (kappa 0.34). In the second round it was good (weighted kappa 0.62). Their agreement on grade was fair in the first round (kappa 0.28) and poor in the second (weighted kappa 0). When each pathologist's two rounds were compared, agreement on subtype was fair (0.27) for one and moderate (0.44) for the other. For grade it was 0 and 0.2. The authors concluded that training and clearer definitions are needed before subtype and grade can be built into mesothelioma classification.

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, descriptive study of agreement between two pathologists and of each pathologist's consistency with themselves, with two rounds of slide review one month apart
• Who was studied: Slides of malignant pleural mesotheliomas diagnosed at a single institution from 2004 to 2017, reviewed by two pathologists experienced in thoracic pathology
• Exposure: Not applicable: the study did not examine asbestos or any other exposure. It examined how pathologists classified tumour slides.
• Main results:
  • 50 malignant pleural mesotheliomas were included
  • Of the cases, 44 (88%) were epithelioid, 4 (8%) sarcomatoid and 2 (4%) biphasic mesothelioma
  • Agreement between the two pathologists on subtyping in the first round: Cohen kappa 0.34, fair agreement
  • Agreement between the two pathologists on subtyping after the second round: weighted kappa 0.62, good agreement
  • Agreement between the two pathologists on grading epithelioid tumours: 59% (26/44) concordance and kappa 0.28 (fair) in the first round. After the second round, weighted kappa was 0 (poor).
  • Each pathologist's agreement with their own earlier subtyping was fair (kappa 0.27) for the first reviewer and moderate (kappa 0.44) for the second reviewer
  • Each pathologist's agreement with their own earlier grading was very poor (kappa 0) for reviewer 1 and poor (kappa 0.2) for reviewer 2
  • The discussion between the reviewers improved agreement on subtyping but had no effect on agreement on grading
• The authors' conclusion: The authors concluded that training, and more precise definitions of the microscopic features, are needed before subtype and grade can be integrated into the classification of malignant mesotheliomas.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Epithelioid, Mesothelioma, Nuclear Grade, Pathology, Habit.

Related studies

• Interobserver variation in the assessment of the sarcomatoid and transitional components in biphasic mesotheliomas — S. Dacic, N. Le Stang, et al. (2020)
• Reproducibility of Malignant Pleural Mesothelioma Histopathologic Subtyping — L. Brcic, G. Vlacic, et al. (2018)
• Reproducibility of histological subtyping of malignant pleural mesothelioma — L. Brčić, M. Jakopović, et al. (2014)
• Malignant mesothelioma of the pleura: interobserver variability — A. Andrion, C. Magnani, et al. (1995)
• Reproducibility for histologic parameters in peritoneal mesothelioma — D.J. Hartman, A. Borczuk, et al. (2017)
• The histopathological diagnosis of malignant mesothelioma v. pulmonary adenocarcinoma: reproducibility of the histopathological diagnosis — B.G. Skov, A.F. Lauritzen, et al. (1994)

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