The Significance of Urothelial Cell Clusters in Voided Urine Specimens
Beatrice B Lee, Xin Jing, Judy C Pang, Michael H Roh. University of Michigan Health System, Ann Arbor, MI
Background: The cytomorphologic examination of voided urine is commonly employed to screen for and detect urothelial cell carcinoma (UCC). The significance of the “atypical” interpretive category for urine cytology is uncertain. Adding to this uncertainty is the debatable significance of urothelial cell clusters in voided urine. The etiologic differential diagnosis includes urinary tract stones, recent urinary tract instrumentation, and neoplasia; however, some experts argue that urothelial cell clusters in voided urine should be regarded as benign findings. As the literature on the significance of urothelial cell clusters in voided urine is sparse, we retrospectively analyzed a large cohort of patients for whom clusters of urothelial cells were observed in voided urine specimens.
Design: A total of 542 patients, found to have clusters of urothelial cells in voided urine samples between 2000 and 2011, with at least one-year of clinical follow-up were identified. For each, the electronic medical records were examined for the following: prior history of UCC, cystoscopy notes, operative reports, radiology reports for urinary tract calculi, and subsequent histopathologic followup. For comparison of malignancy rates within this cohort, patients were stratified based on presence/absence of urinary tract calculi, prior history of UCC, and history of recent urinary tract instrumentation.
Results: Overall, UCC was diagnosed on follow-up surgical pathology specimens in 102 (18.8%) of 542 patients. Urinary tract calculi were present in 103 (19.0%) and absent in 439 (81.0%) of the 542 patients at the time of voided urine collection. UCC was subsequently diagnosed in 4 (3.9%) of 103 patients with calculi and in 98 (22.3%) of 439 patients without calculi (p<0.0001). Next, 171 (31.5%) and 371 (68.5%) of the 542 patients had or did not have a prior history of UCC at the time of voided urine collection, respectively. On follow-up, UCC was diagnosed in 57 (33.3%) of 171 patients with a prior history of UCC and 45 (12.1%) of 371 patients without a previous history of UCC (p<0.0001). Finally, a history of recent urinary tract instrumentation was documented in 17 (3.1%) of 542 patients; the malignancy rate in this subset of patients was 4 (23.5%) of 17. UCC was diagnosed on follow-up for 98 (18.7%) of 525 patients without a history of recent instrumentation (p=0.54).
Conclusions: The presence of urothelial cell clusters in voided urine is clinically relevant and should not be equated with a negative interpretation. A prior history of UCC and absence of urinary tract calculi represent significant predictors of UCC on follow-up.
Tuesday, March 5, 2013 1:00 PM
Poster Session IV # 102, Tuesday Afternoon