Published in Cancer Detection and Prevention 2001; 25(2):202-209.

Cytokeratin 20 as an Immunocytochemical Marker for Detection of Urothelial Carcinoma in Atypical Cytology: Preliminary Retrospective Study on Archived Urine Slides.

Suhua Lin, Sharon L. Hirschowitz, Carol Williams, Peter Shintako, Jonathan Said, and JianYu Rao, MD

Department of Pathology and Laboratory Medicine and Jonsson Comprehensive Cancer Center, University of California at Los Angeles Medical Center, Los Angeles, CA

Address all correspondence and reprint requests to: J. Rao, MD, Department of Pathology and Laboratory Medicine, University of California at Los Angeles Medical Center, Los Angeles, CA 90095.

ABSTRACT: Previous studies have shown that expression of cytokeratin 20 (CK2O), a constituent of intermediate filaments, is increased in malignant versus benign urine samples. To evaluate whether immunocytochemical staining of CK2O on archived urine slides could be used as a potential adjunct marker for triage of atypical urine cytology, we analyzed a total of 77 archived urine slides obtained from a spectrum of patients with various risks of developing urothelial carcinoma. These patients were divided into four groups on the basis of initial urine cytologic results and subsequent follow-up biopsy findings; group 1 had negative results in both evaluations, whereas the results in group 4 were positive for both cytology and biopsy. Groups 2 and 3 had a diagnosis of atypical urine cytology; however, patients in group 3 had a positive follow-up biopsy, and patients in group 2 did not. The Papanicolaou-stained archived urine slides were destained and then restained immunocytochemically with monoclonal antibody against CK2O. With 5% positively stained nonumbrella cells as a threshold, CK2O was positive in 94.4% of group 3 or 4 patients. In contrast, CK2O was positive in 27.3% of group 2 patients and in 10.5% of group I patients. The overall sensitivity and specificity for CK2O for the detection of urothelial carcinoma in this population of patients were 94.4% and 80.5%, respectively. This study demonstrated that immunocytochemical analysis of CK2O on archived urine slides could be used to triage atypical urine cytology into low- and high-risk categories and that CK2O might be a simple and useful early detection marker for urothelial carcinoma.

KEY WORDS: atypical urine cytology, cytokeratin 20, early detection, immunocytochemistry, urothelial carcinoma.