Basement membrane patterns in borderline tumors of the ovary. An immunohistochemical study with antibodies to laminin and type IV collagen.

Using antibodies directed against the basement membrane (BM) components laminin and type IV collagen, basement membrane patterns were studied in borderline epithelial tumors of the ovary. To determine the potential use of BM immunohistochemistry in the histopathologic diagnosis of tumors of borderline category, BM patterns were compared with those in cystadenomas and cystadenocarcinomas. In cystadenomas, regular and intact BM were found at the interface between the epithelial cells of the cysts and the adjacent stroma. Cystadenocarcinomas displayed an irregular pattern, with areas of intact BM between tumor cells and stroma, as well as areas with irregular discontinuities. Tumors of borderline malignancy shared a continuous BM pattern with cystadenomas, However, 30% of the borderline malignant tumors contained small areas with BM interruptions resembling those of invasive carcinoma. From the results of this study we conclude that BM patterns in ovarian tumors of borderline malignancy are mostly similar to those of benign epithelial tumors. Focal defects possibly indicating early invasive growth, however, occur in 30% of the cases.