Gleason Grade 4 Prostate Adenocarcinoma Patterns: An Inter-observer Agreement Study among Genitourinary Pathologists.

AIMS - To assess the inter-observer reproducibility of individual Gleason grade 4 growth patterns.

METHODS - Twenty-three genitourinary pathologists participated in the evaluation of 60 selected high-magnification photographs.

The selection included 10 cases of Gleason grade 3, 40 Gleason grade 4 (10 per growth pattern) and 10 Gleason grade 5. Participants were asked to select a single predominant Gleason grade per case (3, 4, 5) and to indicate the predominant Gleason grade 4 growth pattern if present. "Consensus" was defined as at least 80% agreement and "favoured" as 60-80% agreement.

RESULTS - Consensus on Gleason grading was reached in 47/60 (78%) cases, 35 of which were assigned a grade 4. In the 13 non-consensus cases, ill-formed (6/13, 46%) and fused (7/13, 54%) patterns were involved in disagreement. Among the 20 cases where at least 1 pathologist assigned the ill-formed growth pattern none (0%, 0/20) reached consensus. Consensus for fused, cribriform and glomeruloid glands was reached in 2%, 23%, and 38%, respectively. In 9/35 (26%) consensus Gleason grade 4 cases, participants disagreed on growth pattern. Six of these were characterized by large epithelial proliferations with delicate intervening fibro-vascular cores, which were alternately given fused or cribriform growth pattern ("complex fused").

CONCLUSIONS - Consensus on Gleason grade 4 growth pattern was predominantly reached on cribriform and glomeruloid patterns, but rarely on ill-formed and fused glands. The complex fused glands seem to be a borderline pattern of unknown prognostic significance on which a consensus could not be reached. This article is protected by copyright. All rights reserved.

Histopathology. 2016 Mar 30 [Epub ahead of print]

Charlotte F Kweldam, Daan Nieboer, Ferran Algaba, Mahul B Amin, Dan M Berney, Athanase Billis, David G Bostwick, Lukas Bubendorf, Liang Cheng, Eva Compérat, Brett Delahunt, Lars Egevad, Andrew J Evans, Donna E Hansel, Peter A Humphrey, Glen Kristiansen, Theodorus H van der Kwast, Cristina Magi-Galluzzi, Rodolfo Montironi, George J Netto, Hemamali Samaratunga, John R Srigley, Puay H Tan, Murali Varma, Ming Zhou, Geert J L H van Leenders

Department of Pathology, Erasmus Medical Center, Rotterdam, The Netherlands., Department of Public Health, Erasmus Medical Center, Rotterdam, The Netherlands., Department of Pathology, Universitat Autónoma de Barcelona, Barcelona, Spain., Department of Pathology & Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, USA., Department of Cellular Pathology, The Royal London Hospital, London, UK., Department of Anatomic Pathology, School of Medical Sciences, State University of Campinas (Unicamp), Campinas, Brazil., Bostwick Laboratories, Orlando, FL, USA., Institute for Pathology, University Hospital Basel, Basel, Switzerland., Department of Pathology & Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA., Service d'Anatomie & Cytologie Pathologiques du Pr Capron, Hôpital de la Pitié-Salpêtrière, Paris, France., Department of Pathology and Molecular Medicine, Wellington School of Medicine and Health Sciences, University of Otago, Wellington, New Zealand., Department of Oncology and Pathology, Karolinska University Hospital, Solna, Stockholm, Sweden., Department of Pathology & Laboratory Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada., Department of Pathology, University of California San Diego, La Jolla, CA, USA., Department of Pathology, Yale University School of Medicine, New Haven, CT, USA., Institute of Pathology, University of Bonn, Bonn, Germany., Department of Pathology & Laboratory Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada., Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH, USA., Section of Pathological Anatomy, Department of Biomedical Sciences and Public Health, Polytechnic University of the Marche Region (Ancona), Ancona, Italy., Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, USA., Aquesta Pathology and University of Queensland, Brisbane, Qld, Australia., Trillium Health Partners, Mississauga and McMaster University, Hamilton, ON, Canada., Department of Pathology, Singapore General Hospital, Singapore., Department of Medical Genetics, Haematology and Pathology, Cardiff University, Cardiff, UK., Department of Pathology, NYU Langone Medical Center, New York, NY, USA., Department of Pathology, Erasmus Medical Center, Rotterdam, The Netherlands.