Accuracy of Urine Cytology and the Significance of an Atypical Category

TLDR

The atypical urothelial cell cytologic category is nonstandardized and its overall clinical significance is unclear. The study assessed the predictive value of atypical cytology by examining histologic follow‑up. The authors subclassified atypical cases into “atypical, favor a reactive process” and “atypical, unclear if reactive or neoplastic,” and reviewed histologic follow‑up for 282 of 1,114 patients across 3,261 specimens. Atypical cytology did not confer a significantly higher risk of urothelial neoplasia versus benign, and although the “atypical unclear” subgroup showed a higher, non‑significant rate of high‑grade cancer, subdividing atypical cases did not provide clinically relevant information.

Abstract

The "atypical urothelial cell" cytologic category is nonstandardized. We subclassify atypical cases to "atypical, favor a reactive process" or "atypical, unclear if reactive or neoplastic." We evaluated the predictive significance of atypical cases by looking at their histologic follow-up. Among the 1,114 patients and 3,261 specimens included, 282 specimens had histologic follow-up. An atypical diagnosis did not carry a significant increased risk of urothelial neoplasia compared with the benign category. Although an "atypical unclear" diagnosis carried a higher rate of detection of high-grade cancer on follow-up biopsy in comparison with "atypical reactive" or "negative" diagnoses (26/58 [45%] vs 15/52 [29%] and 16/103 [15.5%], respectively), this difference was not statistically significant. These results suggest that dividing atypical cases into 2 categories based on the level of cytologic suspicion of cancer does not add clinically relevant information within the atypical category. They also raise the question of the significance of the atypical category altogether.