Urothelial dysplasia: Diagnostic value in clinical practice 20 years since the 1998 who/isup consensus

Background: In the 1980-90s, flat neoplastic urothelial lesions were categorized as mild, moderate, and severe dysplasia, and urothelial carcinoma in situ (CIS). Three subsequent WHO classifications have condensed these lesions into urothelial dysplasia and CIS, with CIS including many lesions with moderate to severe dysplasia. Many suggest \u27dysplasia\u27 is infrequent in diagnostic specimens, but little is known of the use of this term in contemporary practice. Design: We surveyed 45 academic uropathologists practicing in 12 countries on their diagnostic practices regarding \u27dysplasia\u27. Deidentified responses to both specific questions regarding diagnostic practice and opinions regarding dysplasia diagnosis in prior and future practice were tabulated. Results: Most respondents diagnosed dysplasia (82%) in the past 10 years, though many noted rarity of usage. Of those who have diagnosed dysplasia (N=37), 38% had done so in a de novo setting, although the majority (86%) made the diagnosis in the setting of antecedent urothelial neoplasm. Further, 31% have diagnosed dysplasia in the upper tract, 39% have diagnosed multifocal dysplasia, 56% diagnosed it with concurrent CIS or papillary neoplasm, and 33% used IHC to assess dysplasia versus CIS. Of those who did not diagnose dysplasia (N=8, 18%), all have reported the possibility of dysplasia in biopsies labeled \u27atypical\u27. Most (83%) consider dysplasia a relevant concept in the pathogenesis of urothelial neoplasms and nearly all (91%) support greater study. Only a minority (11%) could identify any important work supporting dysplasia as a distinct entity in two decades. Overall, nearly half of the participants were for (56%) or against (44%) prospective use of \u27dysplasia\u27 in practice. Conclusions: Among academic uropathologists, there is striking variation in the use of \u27urothelial dysplasia\u27 across diagnostic settings. Most who use the term use it in biopsies with prior or concurrent urothelial neoplasia; some avoid the term, preferring \u27atypia\u27 for lesions falling short of CIS. This discrepancy confirms need for a diagnostic term for lesions with features believed neoplastic but insufficient to designate as CIS. The decrease in urologic pathologists who favor future use of \u27dysplasia\u27 diagnosis (56%) compared to those reporting prior use of the term (84%) may signal the opportunity to promulgate improved terminology to communicate diagnostic concern and uncertainty. Future study will be needed to inform recommended follow-up and management