E-cadherin cell-adhesion molecule expression as a diagnostic adjunct in urothelial cytology.

E-cadherin (E-CD) is a cell-adhesion molecule that has been associated with invasion and metastasis in a wide variety of human neoplasms. We have recently shown that, although decreased E-CD expression is associated with increased bladder-wall invasion and higher tumor grade of infiltrating transitional cell carcinomas (TCC), E-CD expression in the exophytic portion of pure papillary and papillary-infiltrating TCC is increased over that of normal transitional cells. To evaluate whether E-CD levels could serve as a diagnostic adjunct in urinary cytology specimens, we stained 40 alcohol-fixed bladder-washing cytospin preparations with an avidin-biotin-peroxidase method using a monoclonal antibody to E-CD (Sigma Chemical Co., St. Louis, MO). E-CD expression level was defined as a high-intensity or low-intensity staining increase over background squamous cell staining for the transitional cells in 21 biopsy-proven transitional cell carcinomas with papillary components, and in 19 benign or reactive control specimens. Twenty-one of 21 TCC (100%) showed an increased E-CD level over background, with 13 low-intensity and 8 highintensity cases. Ten of 19 benign cases (53%) showed increased E-CD staining over background, with 8 low-intensity and 2 highintensity cases. This difference between malignant and benign specimens was statistically significant (chi-square test. P approximately 0.001). We conclude that increased E-CD expression in the papillary components of TCC can be identified in urinary cytology specimens, may reflect the physical and chemical structural makeup of papillary architecture, and warrants further study as a diagnostic adjunct in the interpretation of urine cytology specimens.