Background: The aim of this study was to evaluate 10 years of false positive urine cytology records, along with 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 2002 and December 2012 from voided and catheterized urine from the bladder. Among the 21,283 urine samples obtained during this period, we located 1,090 eligible false positive findings for patients being evaluated for the purpose 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. Patients with concomitant UC accounted for 105 (23.6%) of the atypical samples, 147 (40.1%) of the indeterminate samples, and 139 (49.8%) of the suspicious of malignancy samples (p<0.0001). The rate of subsequent diagnosis of UC during a 1-year follow-up period after harvesting of a sample with false positive urine cytology initially diagnosed 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 indeterminate samples, and 199 (71.3%) for samples categorized as suspicious of malignancy.
Conclusions: Urine cytology remains the most specific adjunctive method for the surveillance of UC. We demonstrated the clinical value of dividing false positive urine cytology findings into three categories, and our results may help clinicians better manage patients with suspicious findings.