Reproducibility for histologic parameters in peritoneal mesothelioma

Our plain-English summary of Reproducibility for histologic parameters in peritoneal mesothelioma, by D.J. Hartman, A. Borczuk, S. Dacic, et al (Human Pathology, 2017).

The study

• Authors: D.J. Hartman, A. Borczuk, S. Dacic, A. Krasinskas
• Journal: Human Pathology
• Published: 2017;67:54-59
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Histologic subtype is recognized as a prognostic factor in malignant pleural mesothelioma. Specifically, epithelial morphology is associated with a better prognosis than other subtypes, and the same association is observed in peritoneal malignant mesothelioma. Recently, prognostic differences based on morphologic subtypes of epithelial peritoneal malignant mesothelioma were reported. Herein, we report the interobserver variability across four pathologists at three institutions. The authors independently reviewed 67 cases of malignant peritoneal epithelioid mesotheliomas and subclassified them according to their epithelial subtype: papillary, tubulopapillary, trabecular, micropapillary, solid and/or pleomorphic. The cases were also evaluated by each author for several other histopathologic parameters including depth of invasion, nuclear grade, lymphocytic host response, mitotic count/index, presence of lymphovascular invasion, and stromal desmoplasia. The interobserver agreement for histopathologic parameters was highest for mitotic rate (κ=0.36) and primary epithelial subtype (κ=0.32). The interobserver variability for solid subtype pattern was moderate (κ=0.49). We found that the interobserver variability for most histopathologic parameters is poor.

Copyright © 2017 Elsevier Inc. All rights reserved.

In plain English

This study measured how consistently pathologists agree when describing the microscopic features of peritoneal mesothelioma, a cancer of the abdominal lining. It did not study asbestos or any other exposure. Four pathologists at three institutions each reviewed, on their own, digital slide images of 67 epithelial-type malignant peritoneal mesotheliomas from the archives of Columbia University Medical Center. Each recorded the main epithelial subtype (such as solid or papillary) and other features such as mitotic rate and depth of invasion. Agreement was measured with the kappa statistic. Overall agreement on the main subtype was kappa 0.32, which the authors called fair. Agreement on whether a tumor was mainly solid or any other subtype was kappa 0.49, which they called moderate. Agreement was lower for tubulopapillary (0.17) and tubular (0.20), and lowest for micropapillary. Among the other features, mitotic rate scored highest (kappa 0.36) and desmoplastic response lowest (0.07). The authors concluded that agreement was moderate for the solid subtype but poor for the other subtypes. They noted that their study group was relatively small.

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: Interobserver agreement (reproducibility) study: four pathologists at three institutions independently reviewed whole slide images of the same cases, and agreement was measured with the kappa statistic
• Who was studied: 67 malignant peritoneal mesotheliomas of epithelial type from the archives of the Department of Pathology at Columbia University Medical Center, New York. The tumors were removed by debulking surgery and had not been treated with chemotherapy. Of the patients, 64% were male, with an average age of 60 years (range 20 to 88). The years covered are not stated.
• Exposure: Not an exposure study; asbestos and other exposures were not examined. The features assessed were epithelial subtype, depth of invasion, nuclear grade, lymphocytic host response, mitotic count/index, lymphovascular invasion and stromal desmoplasia.
• Main results:
  • Agreement among the four pathologists on the primary epithelial subtype, across all seven subtypes, was kappa 0.32 (described as fair)
  • When solid subtype was compared with all other subtypes grouped together, agreement was kappa 0.49 (described as moderate)
  • Solid was the most frequent primary subtype: 40.2% of cases, averaged across the four reviewers (108 of 268 interpretations in Table 1)
  • Agreement was poor for the tubulopapillary (kappa 0.17) and tubular (kappa 0.20) subtypes
  • The micropapillary subtype had the lowest agreement (Table 2: 0.030303, Prob>Z 0.36). Papillary, trabecular and pleomorphic could not be analyzed statistically because there were too few cases.
  • The reviewers differed in which papillary-type subtype they chose. For example, the papillary subtype was the primary subtype in 19 of 67 cases (28.4%) for reviewer 1 but in 3 of 67 (4.5%) for reviewer 2.
  • Mitotic rate had the highest agreement among the other histologic features, kappa 0.36, which the results section calls moderate
  • Agreement was fair for nuclear grade (kappa 0.28), lymphoid response (kappa 0.22) and lymphovascular invasion (kappa 0.22)
  • Agreement was only slight for sarcomatoid features (kappa 0.20), depth of invasion (kappa 0.14) and desmoplastic response (kappa 0.07; Table 3 Prob>Z 0.052091)
  • At least one of the four reviewers judged a tumor to show a single (pure) epithelial subtype in 13 cases (19%). Solid was the pure subtype in 6 of these 13.
• The authors' conclusion: The authors concluded that agreement was moderate for the solid epithelial subtype and poor for the other subtypes. Among the other features, they found moderate agreement for mitotic index and only poor to fair agreement for the rest. They said future studies of the prognostic value of these subtypes should keep the low agreement in mind.
• Limitations the authors state:
  • The study group was relatively small, although the authors describe it as the largest study of its kind to date
  • No consensus conference was held among the pathologists; the authors say one might have changed the assessments, especially of the papillary subtypes

Topics

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

Medical terms in this study, explained in our Lexicon: Peritoneal Mesothelioma, Histological Subtype, Pleural Mesothelioma, Prognosis, Malignant Mesothelioma, Epithelioid, Mesothelioma, Tubulopapillary.

Related studies

• Combined grade and nuclear grade are prognosis predictors of epithelioid malignant peritoneal mesothelioma: a multi-institutional retrospective study — N. Benzerdjeb, P. Dartigues, et al. (2021)
• Deciduoid mesothelioma: report of 21 cases with review of the literature — N.G. Ordóñez (2012)
• Malignant peritoneal mesothelioma: prognostic significance of clinical and pathologic parameters and validation of a nuclear-grading system in a multi-institutional series of 225 cases — D.B. Chapel, J.J. Schulte, et al. (2021)
• Dedifferentiated Liposarcoma With Epithelioid/Epithelial Features — N. Makise, A. Yoshida, et al. (2017)
• A nuclear grading system is a strong predictor of survival in epitheloid diffuse malignant pleural mesothelioma — K. Kadota, K. Suzuki, et al. (2012)
• Diffuse Malignant Peritoneal Mesothelioma Presenting with Psammomatous Calcification on a Cervical Smear — A. Tan, P. Cohen, et al. (2015)

Browse more research in Human Pathology, or return to medical research.