A Validation Study of an Expanded Description of Glandular (Acinar)/Tubule Formation for the Use of Nottingham Grading System for Invasive Breast Carcinomas Demonstrates Improvement in Concordance for Breast Pathologists and Trainees in Pathology
Context.—
The Nottingham grading system, developed by Elston and Ellis, is the recommended method for grading invasive breast carcinoma. A previous study demonstrated the mean concordance for 35 breast pathologists in classifying 58 images as glandular (acinar)/tubule formation (G/TF) based on the World Health Organization definition was only 64%.
Objective.—
To determine if an expanded description of G/TF according to the original definition and current use of the Nottingham grading system would improve recognition of G/TF among breast pathologists and pathologists in training.
Design.—
Fifty-eight images with one structure circled were classified as G/TF or non-G/TF by Dr Ian Ellis. Images were sent as a PowerPoint (Microsoft) file to the breast pathologists who participated in the original study and to 21 trainees. Participants were asked to classify the structures based on the expanded description and were also provided with the 58 images from the first study with annotation.
Results.—
Among the participating 28 of the original 35 breast pathologists, the mean concordance increased from 64% (range, 40%–97%) to 94% (range, 86%–100%). Trainees had a mean concordance of 90% (range, 52%–100%).
Conclusions.—
The expanded description assisted in the recognition of G/TF for both breast pathologists and trainees. The most important impact on grading will likely be for carcinomas with complex cribriform patterns or micropapillary patterns with “inverted tubules.” Participants endorsed that the expanded description of G/TF and the annotated images would be helpful reference material for pathologists.
Contributor Notes
The authors have no relevant financial interest in the products or companies described in this article.
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Presented at the United States and Canadian Academy of Pathology 112th Annual Meeting; March 13, 2023; New Orleans, Louisiana; and at the United States and Canadian Academy of Pathology 113th annual meeting; March 27, 2024; Baltimore, Maryland.
Karakas and Aldrees are co-first authors