EPITHELIAL MEMBRANE ANTIGEN EXPRESSION IN EPENDYMOMAS

Abstract
Twenty-seven ependymomas were studied (18 ''benign'' or low grade and nine ''malignant'' or high grade) by means of a monoclonal antibody to epithelial membrane antigen (E29) and an antiserum to glial fibrillary acidic protein (GFAP). The E29 antibody reacted with ''benign'' ependymomas but not with ''malignant'' ones. Staining was located on the cell surface and especially that facing rosette lumina. Cells forming papillary structures and ependymal epithelium showed a similar distribution of staining. Glial fibrillary acidic protein (GFAP) reactivity was seen in all tumours, with a perivascular accentuation in ''malignant'' ones. Staining occurred in the cytoplasm of scattered cells and in those forming papillary structures, ependymal epithlium and rosettes. Our results may have implications in relation to the cytogenesis of these tumours and may also be useful in the histological assessment of ''benign'' versus ''malignant'' ependymomas.