[Contribution of immunohistochemical methods to the study of central nervous system tumors]

The contributions of the immunoperoxidase technique for the demonstration of glial fibrillary acidic (GFA) protein, neuron specific enolase (NSE) and the Leu-7 (HNK-1) monoclonal antibody in central nervous system (CNS) tumors are reviewed. GFA protein is expressed in normal, reactive and neoplastic cells of astrocytic lineage. Its presence in nonastrocytic CNS tumors is related either to the development of gliofibrillogenesis (ependymomas), to ontogenetic factors (oligodendrogliomas; choroid plexus papillomas), or to uptake of the protein from adjacent reactive astrocytes (capillary hemangioblastomas). It has permitted the recognition of new entities such as the pleomorphic xanthoastrocytoma, and of little known variants such as lipidized glioblastomas. NSE is of diagnostic importance in peripheral neuronal, endocrine and neuroendocrine tumors, but of considerably less value in CNS tumors, since it may be found in the cells of a variety of glial and other cerebral neoplasma as well as in reactive astrocytes. It has also been found to be present in a number of unrelated tumors outside the nervous system. The Leu-7 (HNK-1) monoclonal antibody, a hematological marker, has been found to cross-react with a number of cells of schwannian origin and may be helpful in the differential diagnosis of schwannomas and neurofibromas from other soft tissue neoplasms. Its recognition of oligodendroglial tumor cells has been confirmed, but it is also frequently recognized by both reactive and neoplastic astrocytes. In addition to its reactivity with cells of the immune system, a number of epithelial tumors, in particular adenocarcinomas of the prostate, will also be recognized by the antibody.(ABSTRACT TRUNCATED AT 250 WORDS)