Meningiomas. An immunohistochemical study of 50 cases.

Fifty formalin-fixed, paraffin-embedded meningiomas were studied with a panel of ten antibodies directed against epithelial antigens, intermediate filaments, and neuroectodermal antigens. Twenty-five (50%) of these were stained with monoclonal antibodies (MoAb) to epithelial membrane antigen (EMA), 12 (24%) with keratin antibodies, 9 (18%) for vimentin, and 4 (8%) for S100 protein. Monoclonal antibodies to Leu-7, desmin, neurofilament 200 kDa, and glial fibrillary acidic protein (GFAP) all failed to stain any of the 50 neoplasms. Overall, 34 (68%) meningiomas stained with one or more antibodies. Sixteen (32%) failed to stain at all. The dual epithelial and mesenchymal nature of meningiomas is supported in this study. Applications to diagnostic surgical pathology and histogenetic implications are discussed.