Cytologic features of urothelial carcinoma in catheterized urine with cellular fragments

OBJECTIVE: To identify architectural and cytomorphologic differences that might help distinguish urothelial neoplasms from instrumentation artifact. STUDY DESIGN: We examined 73 cytologic smears of catheterized urine containing urothelial cell clusters between 1998 and 2004. All patients had at least 1 follow-up biopsy. Smears were reviewed for several morphologic features blindly, without knowledge of the follow-up diagnosis. RESULTS: Of the 73 smears, 39 had a benign diagnosis on follow-up biopsy, and 34 had urothelial carcinoma. Cytoplasmic collar, regular and rounded fragment borders, and fine nuclear chromatin were statistically more common in benign smears than those with urothelial carcinoma (p < 0.0001). No significant differences were identified with regard to the presence of background inflammation or nucleoli in the urine specimens. Of the 17 smears that had a cytoplasmic collar, regular fragment borders and fine nuclear chromatin, only 1 (6%) was found to have urothelial carcinoma on follow-up biopsy. All 20 smears in which all 3 features were absent were proven malignant on biopsy. CONCLUSION: Certain architectural and nuclear features can help differentiate urothelial neoplasms from instrumentation artifact in urine cytologic smears.