In urothelial low-grade carcinomas of the bladder stage pT1, prognosis in general is good. In a subset of these tumors infiltrating beyond the lamina muscularis mucosae, prognosis clearly worsens. Unfortunately, evaluation of the lamina muscularis mucosae often is very difficult or even impossible because of its incomplete extension. In an immunohistochemical study on 131 pTa and pT1 urothelial tumors without provable lamina muscularis mucosae, we evaluated the proliferative activity with the monoclonal antibody MIB-1 and the expression pattern of cytokeratins of high molecular weight with the monoclonal antibody 34betaE12. The highest proliferative indices were found in tumors with a diffuse expression pattern of MIB-1 and 34betaE12. A preliminary analysis of follow-up data showed that 70.6% of the pT1 GIb-GIa tumors that recurred showed a diffuse expression pattern for both markers. Whether these patients are candidates for a doser follow-up or even for a more radical therapy has to be subject to further follow-up studies.
