Malignant mesothelioma of the pleura: interobserver variability

Our plain-English summary of Malignant mesothelioma of the pleura: interobserver variability, by A. Andrion, C. Magnani, P.G. Betta, et al (Journal of Clinical Pathology, 1995).

The study

• Authors: A. Andrion, C. Magnani, P.G. Betta, A. Donna, F. Mollo, M. Scelsi, P. Bernardi, M. Botta, B. Terracini
• Journal: Journal of Clinical Pathology
• Published: 1995;48(9):856-60
• Cited by: 57 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Aims: To assess the consistency of histopathological diagnosis of pleural malignant mesothelioma by estimating interobserver agreement between five pathologists.

Methods: Eighty eight histological sets pertaining to original diagnoses of pleural malignant mesothelioma were reviewed separately by each pathologist. Diagnostic likelihood was graded as definite (A), probable (B), possible (C), improbable (D), and definitely not (E) malignant mesothelioma. The following indexes were estimated: observed proportion of agreement (Po), kappa statistics and proportion of agreement for "positive" (Ppos) and "negative" (Pneg) diagnoses.

Results: Sixty cases (68.2%) were rated by at least three reviewers as A or B and by none of the others as D or E. Five (5.7%) were rated by at least two reviewers as D or E and by none of the others as A or B. Nine (10.2%) showed a serious disagreement, rated A or B and D or E. Agreement for sets obtained at necropsy/surgery (median kappa w = 0.57) was similar to that for endoscopic material (median kappa w = 0.54). Agreement was poor on material obtained by needle biopsy (median kappa w = 0.21). The median value of Ppos varied between 0.94 (necropsy/surgery) and 0.67 (needle biopsy) and that of Pneg between 0.78 (necropsy/surgery) and 0.34 (unspecified biopsy). Interobserver agreement on histological typing was good overall (median kappa = 0.59).

Conclusions: Of the original histological diagnoses, 70% were consistently reproduced through panel review. Most indexes of agreement between pathologists ranged from poor (needle biopsy) to moderate (necropsy/surgery). Agreement in confirming malignant mesothelioma was greater than that regarding exclusion of this diagnosis. Of the cases finally considered to have malignant mesothelioma, the reproducibility of histological typing was relatively satisfactory.

In plain English

This study tested how consistently pathologists agree when diagnosing malignant mesothelioma of the pleura from tissue slides. It used 88 sets of slides from 83 patients diagnosed on histology between 1980 and 1989 in the Casale Monferrato district of northwest Italy, where an asbestos cement plant had operated until 1985. Five pathologists separately reviewed the haematoxylin and eosin stained slides without knowing the original diagnosis or patient details. They graded each case on a scale from definite to definitely not mesothelioma, or as unsatisfactory material for diagnosis. Sixty cases (68.2%) were rated definite or probable by at least three reviewers and improbable or definitely not by none, while nine (10.2%) showed serious disagreement. Agreement, measured by weighted kappa, was similar for material from necropsy or surgery (median 0.57) and endoscopic biopsy (median 0.54), but poor for needle biopsy (median 0.21). Agreement on confirming the diagnosis was greater than on excluding it. The authors concluded that 70% of original diagnoses were consistently reproduced. They noted that the lack of agreement may relate to reviewing slides alone.

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 study: five pathologists independently and blindly reviewed original histological slides of diagnosed cases
• Who was studied: 88 sets of slides from 83 patients (50 men, 33 women) originally diagnosed on histology with pleural malignant mesothelioma in the Casale Monferrato district, northwest Italy, between 1980 and 1989
• Exposure: Asbestos exposure was not measured in this study. It was background only: an asbestos cement plant had operated in the district until 1985, and reviewers were not told patients' occupational exposure history.
• Main results:
  • Sixty of 88 cases (68.2%) were rated definite or probable mesothelioma by at least three reviewers and improbable or definitely not by none of the others
  • Five cases (5.7%) were rated improbable or definitely not by at least two reviewers and definite or probable by none of the others
  • Nine cases (10.2%) showed serious disagreement, with ratings of both definite/probable and improbable/definitely not
  • The remaining 14 cases (15.9%) were rated by most reviewers as possible mesothelioma or as unsatisfactory material
  • Agreement for material from necropsy or surgery (median weighted kappa 0.57) was similar to that for endoscopic material (median 0.54)
  • Agreement was poor for material from needle biopsy (median weighted kappa 0.21)
  • Agreement on negative diagnoses (median Pneg) was lower than agreement on positive diagnoses (median Ppos). Median Ppos ranged from 0.94 (necropsy/surgery) to 0.67 (needle biopsy). Median Pneg ranged from 0.78 (necropsy/surgery) to 0.34 (unspecified biopsy).
  • Among cases rated definite or probable, agreement on histological type (epithelial, mixed, fibrosarcomatous) was good overall (median kappa 0.59)
  • Of the 14 necropsy cases originally diagnosed as malignant mesothelioma, only 10 were confirmed by the reviewers
  • All subjects but one died within five years of the original histological diagnosis
• The authors' conclusion: The authors concluded that 70% of the original histological diagnoses were consistently reproduced by the panel. Most agreement indexes ranged from poor (needle biopsy) to moderate (necropsy/surgery). Agreement in confirming mesothelioma was greater than in excluding it. Reproducibility of histological typing was relatively satisfactory.
• Limitations the authors state:
  • Only haematoxylin and eosin stained slides were given to the panel. Additional histochemical and immunohistochemical slides, available for a small number of cases, were not considered.
  • The kappa index is influenced not only by agreement but also by disease prevalence and imbalance of marginal totals, which applies to a series like this one, where all cases had the same original diagnosis
  • Because a full clinico-pathological study has been suggested as the best approach to diagnosis, the authors noted that the lack of agreement may be related to reviewing histological material alone

Topics

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

Medical terms in this study, explained in our Lexicon: Malignant Mesothelioma, Pleura, Autopsy, Needle Biopsy, Biopsy.

Related studies

• Interobserver variability in analysis of asbestos fibres and asbestos bodies in human lung tissue — F. Roberts, J.L. Mackinnon, et al. (2004)
• Interobserver Variability of Quantitative and Qualitative Assessment Using MRI in Malignant Pleural Mesothelioma — R.R. Gill, D.J. Murphy, et al. (2020)
• Interobserver variation in the assessment of the sarcomatoid and transitional components in biphasic mesotheliomas — S. Dacic, N. Le Stang, et al. (2020)
• Interobserver Agreement in Histopathological Subtyping of Malignant Pleural Mesotheliomas — M. Mlika, F. Mezni (2021)
• Interobserver variations in diagnosing asbestosis according to the ILO classification — I. Perić, K. Novak, et al. (2009)
• Influence of inter-observer delineation variability on radiomics stability in different tumor sites — M. Pavic, M. Bogowicz, et al. (2018)

Browse more research in Journal of Clinical Pathology, or return to medical research.