Benign-appearing urothelial tissue fragments in noninstrumented voided urine specimens are associated with low rates of urothelial neoplasia.

BACKGROUND

The presence of urothelial tissue fragments (UTF) in voided urine (VU) is often considered an abnormal finding that may be associated with the presence of urothelial papillary neoplasms. In the current study, the authors reviewed VU specimens containing benign-appearing UTF (BUTF) to determine the associated rate of urothelial neoplasia at the study institution.

METHODS

A retrospective search of the electronic pathology database system over a 5-year period (2009-2013) revealed 1131 VU specimens containing UTF. Of these, 459 cases (40.6%) did not have a recent history of instrumentation. Fifteen cases were excluded because the slides were not available for review. In the remaining 444 cases, 274 cases (61.7%) had BUTF. A total of 170 cases (38.3%) had UTF with atypical cytologic features and were therefore excluded.

RESULTS

Of the 274 cases, 29 (10.6%) had follow-up surgical pathology specimens available. The overall rate of urothelial neoplasia on follow-up was 3.6% for low-grade urothelial neoplasia (10 cases) and 0.7% for high-grade urothelial carcinoma (2 cases). Forty-five cases (16.4%) were determined to have urinary tract stones on follow-up.

CONCLUSIONS

The presence of BUTF in VU specimens requires careful examination of the medical history because their presence may be explained by recent instrumentation. If recent instrumentation is not identified, the etiology of BUTF is not usually determined; in the current study, BUTF were found to be associated with urinary tract stones in 16.4% of cases. They also present a low risk of low-grade urothelial neoplasia (3.6%) and high-grade urothelial carcinoma (0.7%) when compared with the overall benign category at the study institution (2.3% [P =.15] and 0.7%, respectively).