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

Abstract

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. 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. 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. 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.