Clinical Value of Dividing False Positive Urine Cytology Findings into Three Categories: Atypical, Indeterminate, and Suspicious of Malignancy

Background: The aim of this study was to evaluate 10 years of false positive urine cytology records, alongwith follow-up histologic and cytologic data, to determine the significance of suspicious urine cytology findings.Materials and
Methods: We retrospectively reviewed records of urine samples harvested between January 2002and December 2012 from voided and catheterized urine from the bladder. Among the 21,283 urine samplesobtained during this period, we located 1,090 eligible false positive findings for patients being evaluated for thepurpose of confirming urothelial carcinoma (UC). These findings were divided into three categories: atypical,indeterminate, and suspicious of malignancy.
Results: Of the 1,090 samples classified as false positive, 444 (40.7%)were categorized as atypical, 367 (33.7%) as indeterminate, and 279 (25.6%) as suspicious of malignancy. Patientswith concomitant UC accounted for 105 (23.6%) of the atypical samples, 147 (40.1%) of the indeterminatesamples, and 139 (49.8%) of the suspicious of malignancy samples (p<0.0001). The rate of subsequent diagnosisof UC during a 1-year follow-up period after harvesting of a sample with false positive urine cytology initiallydiagnosed as benign was significantly higher in the suspicious of malignancy category than in the other categories(p<0.001). The total numbers of UCs were 150 (33.8%) for atypical samples, 213 (58.0%) for indeterminatesamples, and 199 (71.3%) for samples categorized as suspicious of malignancy.
Conclusions: Urine cytologyremains the most specific adjunctive method for the surveillance of UC. We demonstrated the clinical value ofdividing false positive urine cytology findings into three categories, and our results may help clinicians bettermanage patients with suspicious findings.