A large-scale consensus study of a diagnostic algorithm for canine and feline mammary tumor histopathology: An attempt to improve inter-observer agreement
Abstract
Histological classification of mammary proliferative lesions in dogs and cats is essential for prognostic and predictive studies, as well as for comparative oncology; however, standardization of diagnoses is highly affected by substantial interobserver variability. In this study, a structured diagnostic algorithm based on the Davis-Thompson Foundation classification was assessed for the ability to improve interobserver agreement in the morphological diagnoses of mammary gland lesions in dogs and cats. Consensus diagnoses of 114 selected mammary lesions (91 canine, 23 feline) made by 16 veterinary pathologists with mammary tumor expertise were used as the gold standard, and 79 veterinary pathologists from 21 countries evaluated digitized whole slides in 2 rounds: a first reading without the algorithm and a second reading with the algorithm. Interobserver concordance was measured using unweighted kappa statistics for lesion category (hyperplastic/dysplastic, benign, malignant) and histological subtype. Across all lesions, agreement was higher for lesion category than for histological subtype. A slight improvement in concordance was observed when applying the algorithm, both for category (k = 0.72, before, and k = 0.73, after) and histotype classifications (k = 0.40, before to k = 0.42, after). Also, by using the algorithm, 73/79 raters (92%) modified at least 1 diagnosis and, among these, approximately two-thirds reached agreement with the gold standard in at least 1 case. Considering histotypes, malignant tumors with mixed epithelial and myoepithelial components showed persistently low agreement. Overall, the algorithm provided a reproducible diagnostic framework that may support training and improve standardization of canine and feline mammary tumor classification.
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Authors: Cristiano Cocumelli, Maria Ines Crescio, Jessica Maria Abbate, Erika Abbondati, Yanad Abou Monsef, Eugene Andrews, Elisabetta Antuofermo, Barbara Bacci, Valeria Baldassarre, Katherine Bauer, Sara Belluco, Wilhelmina Bergmann, Chiara Brachelente, Eleonora Brambilla, Barbara Brunetti, Giovanni Pietro Burrai, Nermin Caliskan, Ana Canadas‐Sousa, Emilie Cloup, Sheryl L. Coutermarsh‐Ott, Déborah Culang, Marko Cvetko, Ilaria d’Aquino, Laura Darie, Davide De Biase, Livia De Paolis, Cecilia Degiovanni, Barbara Ďegli Uberti, Giovanni Di Teodoro, Maria Dimatteo, Claudia Eleni, Niccolò Fonti, Valentina Galietta, Adelina Gama, Stefania Gasparini, Lise Geerinckx, Marta Giacomazzo, Giada Giambrone, Giuseppe Giglia, Francesco Godizzi, Michael H. Goldschmidt, Mitja Gombač, Bethânia Almeida Gouveia, Paula Grest, Valeria Grieco, Gjermund Gunnes, Sean Haugland, Chang Shu He, Annabelle Heier, A. Herrmann, Kristen J. Hill-Thimmesch, Miyuki Hirabayashi, Sevda İnan, Selina Iussich, Yumiko Kagawa, Samuel Kalpers, Eva López-Cabré, Ana Machado, Marta Mainenti, Lorella Maniscalco, Elisabetta Manuali, Francesca Millanta, Margaret A. Miller, Valentina Moccia, Vittoria Montemurro, Andrada Gabriela Negoescu, Frédérique Nguyen, Massimo Orioles, Margherita Orlandi, Orlando Paciello, Francesca Parisi, L. Peña, Stephanie Plog, Marta Polinas, Ilaria Porcellato, Dimitra Psalla, Chloé Puget, Roberto Puleio, Caterina Raso, Roberta Rasotto, Massoud Rezaee Oghazi, Elena Riccardi, Joana Rodrigues‐Jesus, Mariarita Romanucci, Elisa Ruiz-Riera, Alessandra Sfacteria, Sara Soto, C Sprohnle‐Barrera, Marian Aurel Taulescu, Kristina Tekavec, Sara Turchetto, Guillermo Valdivia, Sofia Valente, Dominique Judith Wiener, Hisashi Yoshimura, Valentina Zappulli
Institutions: University of Padua, University of Pennsylvania, Universidade de São Paulo, Universidade do Porto, Universidad Complutense de Madrid, Utah State University, Iowa State University, Norwegian University of Life Sciences, University of Sassari, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise G. Caporale, Synlab Czech (Czechia), University of Glasgow, University of Bern, Freie Universität Berlin, AULSS 2 Marca Trevigiana, University of Zurich, Saitama Medical University, University of Turin, Purdue University West Lafayette, University of Naples Federico II, University of Milan, Texas A&M University, University of Pisa, University of Ljubljana, University of Salerno, University of Teramo, Aristotle University of Thessaloniki, Tekirdağ Namık Kemal University, University of Perugia, Kansas State University, Istituto Zooprofilattico Sperimentale dell'Umbria e delle Marche, Utrecht University, University of Trás-os-Montes and Alto Douro, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, École Nationale Vétérinaire de Toulouse, University of Messina, Virginia–Maryland College of Veterinary Medicine, Nippon Veterinary and Life Science University, VetAgro Sup, Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d'Aosta, Japan Small Animal Medical Center, Oniris, Istituto Zooprofilattico Sperimentale Della Sicilia, IDEXX Laboratories (France), Laboklin (Germany), Istituto Zooprofilattico Sperimentale del Mezzogiorno, UCB Pharma (Belgium), Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, Escola Universitária Vasco da Gama, IDEXX Laboratories (Germany)