Comparison between cytospin and liquid-based cytology in urine specimens classified according to the Paris System for Reporting Urinary Cytology

BACKGROUND: The current study compared ThinPrep urinary cytology and conventional cytospin urinary cytology in the diagnosis of bladder cancer, applying the Paris System for Reporting Urinary Cytology. METHODS: Between January 2010 and December 2011, a total of 3659 urine samples were processed using conventional cytospin methods. Between January 2012 and December 2013, a total of 4186 urine cytological cases were analyzed using ThinPrep methods. In 131 cases (65 processed by conventional cytospin and 66 processed by ThinPrep), a subsequent biopsy was performed. The authors reclassified these cases according to the Paris System and an analysis between the 2 methods with regard to bladder biopsies was performed. RESULTS: No significant differences were observed in terms of sensitivity and specificity between the 2 methods in cases with positive cytology for high-grade carcinoma. According to the Paris System, cases of atypical urothelial cells (AUC) and atypical urothelial cells suspicious for high-grade carcinoma (AUC-H) that were processed using cytospin did not correlate with urothelial carcinoma or with negative biopsies; conversely, the AUC cases processed using ThinPrep appeared to correlate with negative histological biopsies or low-grade urothelial carcinoma. CONCLUSIONS: The results of the current study demonstrated that according to the Paris System, there were no significant differences in sensitivity or specificity for the diagnosis of high-grade urothelial carcinoma or AUC-H between the 2 methods. Cases of AUC should be easy to recognize using Thin Prep rather than cytospin and only AUCs diagnosed with ThinPrep were found to be statistically linked to negative cases for carcinoma or with low-grade urothelial carcinoma.