Brenner tumors but not transitional cell carcinomas of the ovary show urothelial differentiation: immunohistochemical staining of urothelial markers,including cytokeratins and uroplakins

To determine whether Brenner tumors and transitional cell carcinomas (TCCs) of the ovary are urothelial in type, the immunoprofiles of 14 Brenner tumo rs, including three malignant examples, and eight ovarian TCCs were compare d with those of Walthard nests, urothelium, 12 urinary bladder TCCs and 17 ovarian adenocarcinomas (serous, endometrioid, mucinous, and undifferentiat ed type). The immunohistochemical stains used included those for cytokerati ns CKs 5/6, CK7, CK8, CK13, and CK20, vimentin, CA125, and the specific uro thelial differentiation marker uroplakin III. CK7 and CK8 were broadly expr essed in most tumors of ovary and bladder examined, while vimentin was foca lly present in some ovarian TCCs and adenocarcinomas. As in normal and neop lastic bladder urothelium, urothelial markers, including uroplakin III, CK1 3, and CK20, were detected in the epithelial nests of bladder tumors. Brenn er tumor cells also expressed uroplakins Ia and II. CA125 was observed foca lly in some Brenner tumors. In contrast, TCCs of the ovary and Walthard nes ts lacked uroplakins and were essentially negative for CK20 and CK13 but qu ite strongly expressed CA125. This immunophenotype closely resembled that f ound in ovarian adenocarcinomas. Thus, it appears that the only true urothe lial-type ovarian neoplasm is the Brenner tumor, whereas ovarian TCC most l ikely represents a poorly differentiated adenocarcinoma with a morphologic transitional cell pattern. These results may explain the controversies as e xpressed in the recent literature concerning TCC of the ovary and establish its place among the ovarian adenocarcinomas of mullerian type.