Is a consistent cytologic diagnosis of low-grade urothelial carcinoma in instrumented urinary tract cytologic specimens possible? A comparison between cytomorphologic features of low-grade urothelial carcinoma and non-neoplastic changes shows extensive overlap, making a reliable diagnosis impossible

Introduction: The ability to consistently diagnose low-grade urothelial carcinoma (LGUC) in urinary tract cytology (UTCy) specimens remains controversial, as the reported sensitivity of UTCy in the detection of LGUC is as low as 10%. To determine whether a consistent cytologic diagnosis of LGUC is possible, we assessed the presence and frequency of previously described cytomorphologic features of LGUC in UTCy from patients with LGUC and a negative control group.

Materials and methods: Biopsy-proven cases of LGUC from June 1, 2010 to January 31, 2014 were identified; UTCy obtained within 3 months prior to biopsy composed the study group (n = 98). The negative control group consisted of UTCy obtained from patients with negative cystoscopy and biopsy (n = 53). All specimens were masked and reviewed in random order to evaluate 17 cytomorphologic parameters.

Results: Univariate statistical analyses demonstrated that the prevalence of paired cells, clumpy chromatin, and cytoplasmic homogeneity was higher in the study group; however, multivariate analysis did not show these features as significant predictors of LGUC.

Conclusions: No cytomorphologic feature was statistically significant in the LGUC group versus the negative control group. The presence of 3-dimensional papillary structures with fibrovascular cores is diagnostic of LGUC, but it is only seen in a small minority (2 of 98) cases. Our results reemphasize the fact that urinary tract cytology has a low sensitivity for the diagnosis of LGUC and suggest that, instead of striving to detect LGUC in urine specimens, we should concentrate on the clinically relevant goal of urine cytology-the detection of high-grade lesions.