Expression of cytokeratin 20 and CD44 protein in upper urinary tract transitional cell carcinoma: Cytologic-histologic correlation

OBJECTIVE: To explore the potential utility of immunostaining for CK20 and CD44 protein isoforms in evaluating cases of upper urinary tract transitional cell carcinoma (UTTCC). STUDY DESIGN: Of 105 consecutive patients diagnosed cytologically with UTTCC, 33 subsequently underwent open surgical procedures. Cytologic samples from these patients retrieved by aspiration and biopsy, and corresponding surgical specimens were graded and staged using World Health Organization/International Society of Urologic Pathologists criteria. Immunostaining for CK20, CD44 standard (CD44s) and CD44v6 isoform (CD44-v6) was performed on all available cytologic and surgical materials. Expression levels and distributions of these markers were correlated semiquantitatively with grade and stage. RESULTS: Cytologically assigned grade correlated with final histologic grade in 19 of 31 cases examined (61%). However, tumor invasion was not accurately assessable in cytologic samples from the majority of these cases. Statistically significant correlations of both increasing tumor grade and stage with abnormal CK20 expression were found. In addition, a significant relationship between focal CD44 isoform expression loss and tumor grade was identified. However, CD44 isoform expression loss did not significantly correlate with increasing tumor stage. CONCLUSION: Although cytologic tumor grading of UTTCC was accurate, invasion could not be adequately assessed. As an adjunct to morphologic analysis, immunostaining for CK20 and CD44 may aid in the clinical evaluation of UTTCC tumor stage and biologic behavior prior to definitive therapy.