The diagnostic value of cytohistological urine analysis and cytokeratin 20 in malignant and atypical urothelial cells.

INTRODUCTION To determine the ability of cytohistology and cytokeratin 20 (CK 20) expression in malignant and atypical cells (AUC) from urine to serve as a diagnostic tool for assessing urothelial carcinoma (UC). METHODS Diagnoses from 55 urine cytological samples from 55 patients were analyzed and correlated with subsequent biopsy findings. A total of 50 archived urine slides from patients that received a cytological diagnosis and histological follow-up were selected for immunostaining with monoclonal CK 20 antibodies and elaborated by Z-test for proportions. RESULTS The majority of all positive or atypical smears (24; 89%) were confirmed through histological analysis. The majority of urinary cytological diagnoses reported as negative (15; 54%) were also confirmed through biopsies. The overall sensitivity, specificity, PPV, and NPV were 65%, 83%, 89%, and 54%, respectively. All 13 smears cytologically determined to contain malignant cells, with subsequent biopsies confirming UC, exhibited strong positive staining with the CK 20 antibody. All cases evaluated as benign both cytologically and histologically had negative CK 20 staining. Of the 15 AUC cases with lesions confirmed through biopsies, 11 (73%) had atypical cells that stained positive for CK 20. DISCUSSION Our results demonstrate the diagnostic value of urinary cytology and confirm CK 20 as an adjunct marker for the diagnosis of UC and for the triage of AUC.