Cytomorphological characteristics of low-grade papillary urothelial carcinoma for differential diagnosis from benign papillary urothelial lesions: logistic regression analysis in SurePath™ liquid-based voided urine cytology

Objective The diagnosis of low‐grade papillary urothelial carcinoma (LGPUC) in urine cytology specimens is challenging because of its subtle, minimally atypical findings. Furthermore, as SurePath™ liquid‐based cytology (LBC) is becoming a widely used method in urine cytology, the inevitable cytomorphological alterations resulting from this technique call for new morphological diagnostic criteria in LGPUC. Methods Logistic regression analysis was carried out on SurePath slides from surgically proven voided urine specimens. The study was designed to include a test set (n = 141) and a validation set (n = 61), and evaluated significant discriminative parameters between LGPUC and benign papillary urothelial neoplasm (BPUN). Results Of the seven cytological findings that were found to have statistical significance in univariate analysis, five were found to be independent variables: loss of polarity of papillaroid clusters, irregular contours, absence of columnar cells, hobnail features and hyperchromasia. These independent variables had an area under the curve (AUC) of 0.781. Conclusions The distinctive cytological criteria identified above may prove to be helpful in cases in which other conventional criteria for LGPUC are insufficient for diagnosis.