Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody .Glial fibrillary acidic protein (GFAP) is a member of class III of intermediate filament proteins. GFAP is mainly expressed in neuroglia including astrocytes and ependymal cells. . GFAP is a marker of neoplastic glial cells and glial differentiation. It is expressed in CNS tumours (astrocytoma, glioblastoma, oligodendroglioma, medulloblastoma, ependymoma), retinoblastoma, neurilemoma, neurothekeoma, MPNST.