Cytokeratin expression patterns in low-grade papillary urothelial neoplasms of the urinary bladder.

Background: The differential expression patterns of cytokeratin 20 (CK20) and 34betaE12 antigen in low-grade papillary urothelial tumors of the bladder are discussed.

Methods: A retrospective study of 120 patients with low-grade papillary bladder tumors (45 neoplasms of low malignant potential and 75 low-grade WHO G1 carcinomas) was performed. All tumors were graded in accordance with the 1998 World Health Organization/International Society of Urological Pathology (WHO/ISUP) and 1999 WHO classifications. The mean follow-up was 76.6 months (range, 36-168 mos), considering for prognostic purposes the time to first recurrence, or relapse-free interval (RFI), and the total number of recurrent patients. Immunohistochemically, normal or abnormal CK20 and 34betaE12 antigen expression patterns were determined for each patient. CK20 (clone IT-Ks) and a high-molecular weight cytokeratin (clone 34betaE12) were the monoclonal antibodies used in the immunohistochemical study.

Results: Seventy-seven of 120 patients (64.2%) experienced a recurrence during follow-up. In recurrence prediction, the differential expression pattern of both cytokeratins showed a high sensitivity (76.6% for CK20 and 80.5% for 34betaE12 antigen) and a high positive predictive value (85.5% for CK20 and 75.6% for 34betaE12 antigen), although specificity was higher for CK20 (76.7%) than it was for 34betaE12 antigen (53.4%). Independent of adjuvant intravesical chemotherapy, these 2 markers showed a strong statistical correlation (p < 0.001) in univariate studies with both the prediction of disease recurrences and RFI.

Conclusions: CK20 and 34betaE12 antigen have proved to be strong predictive markers of disease recurrences when considering different topographic expression profiles, and, in the authors' opinion, these profiles could be incorporated into follow-up clinicopathologic strategies.