A hybrid-three tier system with low grade (LG), high grade- G2 (HG-G2), high grade- G3 (HG-G3) has been proposed in recognition of, and to help address, the clinical heterogeneity within high grade WHO 2004/2022. We assessed interobserver reproducibility amongst international uropathologists using this three-tier approach.
Papillary Ta nonmuscle invasive bladder cancer (NMIBC) specimens (n = 30) were selected and graded by two uropathologists and assessed using WHO 2004/2022 and WHO 1973 and categorized as LG (n = 15), HG-G2 (n = 8), HG-G3 (n = 7), and photographed at 10× and 20× magnification. Images were circulated via Survey Monkey to invited uropathologists who determined: (1) that image was LG or HG, and (2) if HG, assigned to G2 or G3. Model-based kappa measure of association was used to assess interrater agreement. Eighteen uropathologists:(eight North American, eight European, two other) assessed 60 images with 1076 gradings for analysis. The kappa value amongst Europeans versus North Americans was 0.663 versus 0.647 for 10× images and 0.682 versus 0.623 for 20× images. At 10×, agreement for LG, HG-G2, and HG-G3 was 74.6%, 63.6%, and 92.0%, and at 20× was 64.3%, 63.9%, and 95.2% respectively.
Three-tier grading of papillary Ta NMIBC had substantial interobserver agreement amongst international uropathologists. The recognition of the HG-G3 case reached the highest concordance. North American uropathologists had comparable kappa scores (substantial agreement) to Europeans, despite being unaccustomed to separating HG cases into G2 and G3, demonstrating three-tier grading could be "quickly" adopted by genitourinary experts if endorsed and required by the relevant bodies in their jurisdiction of practice.
Histopathology. 2025 Mar 09 [Epub ahead of print]
Michelle R Downes, Katherine Lajkosz, Ferran Algaba, Yves Allory, Mahul B Amin, Liang Cheng, Sangeeta Desai, Markus Eckstein, Arndt Hartmann, Antonio Lopez-Beltran, Sebastian Mannweiler, Maurits L van Montfoort, Jon Oxley, Gladell P Paner, Hemamali Samaratunga, Steven Shen, Joshua Warrick, Sean R Williamson, Sara E Wobker, Theodorus H van der Kwast
Division of Anatomic Pathology, Department of Laboratory Medicine and Molecular Diagnostics, Precision Diagnostics and Therapeutics Program, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada., Department of Biostatistics, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada., Pathology Department, Fundació Puigvert, Barcelona, Spain., Department of Pathology, Institut Curie, Paris, France., Department of Pathology and Laboratory Medicine, University of Tennessee Health Science Center, Memphis, Tennessee, USA., Department of Pathology and Laboratory Medicine, Brown University Warren Alpert Medical School, Providence, Rhode Island, USA., Department of Pathology, Tata Memorial Centre, Mumbai, India., Institute of Pathology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany., Unit of Anatomical Pathology, Faculty of Medicine, Cordoba University, Cordoba, Spain., Institute of Pathology, Medical University of Graz, Graz, Austria., Department of Pathology, Netherlands Cancer Institute, Amsterdam, The Netherlands., Department of Cellular Pathology, North Bristol NHS Trust, Bristol, UK., Departments of Pathology and Surgery, Section of Urology, University of Chicago, Chicago, Illinois, USA., Department of Pathology, Aquesta Uropathology and University of Queensland, Brisbane, Queensland, Australia., Department of Pathology Genomic Medicine, Houston Methodist Hospital and Weill Cornell Medical College, Houston, Texas, USA., Departments of Pathology and Urology, Penn State College of Medicine, Hershey, Pennsylvania, USA., Pathology and Laboratory Medicine Institute, The Cleveland Clinic, Cleveland, Ohio, USA., Lineberger Comprehensive Cancer Center and Department of Pathology and Laboratory Medicine University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA., Laboratory Medicine Program, Princess Margaret Cancer Center, University Health Network, Toronto, Ontario, Canada.