The predictive value of positive and suspicious urine cytology: Are they different?

Urine cytology evaluation is an effective test in the detection of high-grade urothelial carcinoma (HGUC). While the guideline distinguishes the 2 categories: "positive for HGUC" (PHGUC) and "suspicious for HGUC" (SHGUC), the association between these categories with their subsequent follow-up biopsies remains unclear. This study aims to determine and compare the positive predictive value (PPV) of the specimens in PHGUC and SHGUC categories with their respective histologic diagnoses.

During the period of 03/01/2008 to 07/31/2018, urine cytology cases diagnosed as PHGUC and SHGUC with subsequent bladder biopsy within 12 months were retrieved. All cases were correlated with first biopsy obtained during 12 months of cytology specimen. Biopsy result with HGUC, carcinoma in situ, or non-urothelial carcinoma diagnoses were considered as concordance.

378 cases (229 SHGUC and 149 PHGUC) were identified from 263 patients. For the 229 SHGUC cases, the PPV was 72% (n = 166) and for the 149 PHGUC cases, the PPV was 85% (n = 127). While both categories have high PPV, they are statistically significant (p < 0.0001). Additionally, 33 cases were found to have low-grade urothelial carcinoma (LGUC), constituting a portion of discordant results.

PHGUC and SHGUC categories are both associated with a high risk of malignancy, however, there is a statistically significant difference between them in our study, supporting the PSRUC guidelines of two separate categories. In instances when urine cytology is discordant with biopsy results, further investigation and clinical follow up is warranted. LGUC appears to remain a common pitfall especially in the suspicious category.