(Glial fibrillary acidic protein)
Glial fibrillary acidic protein (GFAP) is an intermediate filament protein. The protein is the smallest (8 nm) of the intermediate filament proteins with a molecular weight of about 51 kDa. In the central nervous system, GFAP is expressed in astrocytes and ependymal cells but not in other glial cells. However, immature oligodendrocytes and immature choroid plexus cells may be GFAP positive. In the peripheral nervous system enteric Schwann cells and satellite cells of human sensory ganglia express GFAP. Outside the nervous system, GFAP is seen in myoepithelial cells and chondroblasts, in the former coexpressed with cytokeratin, in the latter coexpressed with vimentin.
Astrocytoma, ependymoma, glioblastoma, and oligodendroglioma are almost always positive. Plexus carcinoma, ganglioglioma and primitive neuroectodermal tumours (PNET: neuroblastoma a.o.) express GFAP to a varying extent. Schwannoma and neurofibroma frequently express GFAP. Chondroma, chondrosarcoma and pleomorphic adenoma are also GFAP positive in most cases. A few carcinomas (especially from lung and breast) may express GFAP. in paraganglioma GFAP may be detected in sustentacular cells.
Classification of intracranial tumours: identification of glial tumours and of glial differentiation in primitive tumours.
Selected references
Curran AE, White DK, Damm DD, Murrah VA. Polymorphous low-grade adenocarcinoma versus pleomorphic adenoma of minor salivary glands: resolution of a diagnostic dilemma by immunohistochemical analysis with glial fibrillary acidic protein. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2001 Feb;91(2):194-9. McLendon RE, Provenzale J. Glioneuronal tumors of the central nervous system. Brain Tumor Pathol. 2002;19(2):51-8. Review. Horvath E, Kovacs K. Folliculo-stellate cells of the human pituitary: a type of adult stem cell? Ultrastruct Pathol. 2002 Jul-Aug;26(4):219-28. Review. Jay V, Edwards V, Halliday W, Rutka J, Lau R. "Polyphenotypic" tumors in the central nervous system: problems in nosology and classification. Pediatr Pathol Lab Med. 1997 May-Jun;17(3):369-89. Review. Matyja E, Taraszewska A, Zabek M. Phenotypic characteristics of GFAP-immunopositive oligodendroglial tumours Part I: immunohistochemical study. Folia Neuropathol. 2001;39(1):19-26. Morrison CD, Prayson RA. Immunohistochemistry in the diagnosis of neoplasms of the central nervous system. Semin Diagn Pathol. 2000 Aug;17(3):204-15. Review. Rickert CH, Paulus W. Tumors of the choroid plexus. Microsc Res Tech. 2001 Jan 1;52(1):104-11. Review. Sembritzki O, Hagel C, Lamszus K, Deppert W, Bohn W. Cytoplasmic localization of wild-type p53 in glioblastomas correlates with expression of vimentin and glial fibrillary acidic protein. Neuro-oncol. 2002 Jul;4(3):171-8.
05.04.05 - SN/MV/LE