Table 2

Some immunohistochemical techniques currently available to assist in diagnostic problems in tumours of the central nervous system

AntibodyMolecular specificityDiagnostic use
ACTH, adrenocorticotrophin; FSH, follicle stimulating hormone; LH, luteinising hormone; TSH, thyroid stimulating hormone.
Gliofibrillary acidic protein (GFAP)An intermediate filament protein of 52 kDaAstrocytomas and ependymomas
S-100 proteinA family of proteins found in neuroectodermal tissuesCells of neural crest origin and their neoplasms (gliomas, nerve sheath and choroid plexus tumours, melanomas, and granular cell myoblastomas)
SynaptophysinA membrane glycoprotein. Occurs in presynaptic vesicles of neurones, adrenal medulla, and neuromuscular junctionsTumours showing neurosecretory differentiation such as neuroblastoma, neurocytoma, medulloblastoma, paraganglioma, pituitary neoplasms, and a wide variety of neuroendocrine tumours
ChromograninAn acidic protein widely distributed in neuronal tissues and in the secretory granules of endocrine cellsNeuroendocrine cells and their neoplasms
Protein gene product 9.5A member of the ubiquitin C terminal hydroxylase family of proteins found in neurones and nerve fibres, in neuroendocrine cells, and in some non-neural cellsMay be useful as a marker of neurones and the ubiquinated inclusions found in several neurodegenerative diseases
Neurone specific enolaseReacts with the gamma-gamma isoenzyme found in neurones, neuroendocrine cells, and a variety of non-neuronal cell typesNeuroendocrine cells and a wide variety of tumours of the nervous system (gliomas, meningiomas, ependymomas, choroid plexus papillomas, schwannomas, medulloblastomas, and some carcinomas (breast and lung))
Neurofilament antibodiesSeveral antibodies are available that react with the 68 kDa, 160 kDa, and 200 kDa components of neurofilamentsTumours of neural lineage including ganglioneuromas, paragangliomas, neuroblastomas, medulloblastomas, and gangliogliomas
Epithelial membrane antigenFound in the epithelial membrane of a variety of normal tissuesIdentification of tumours of epithelial origin, chordomas, meningiomas, and choroid plexus neoplasms
CytokeratinsThere are numerous antigens expressed by different epithelia and mixtures of antibodies are availableEpithelial tumours, craniopharyngiomas, meningiomas, choroid plexus neoplasms, chordomas, and some germ cell tumours
Pituitary hormonesProlactin, growth hormone, ACTH, FSH, LH, and TSHNeoplasms of the pituitary gland
Embryonal cell markers: placental alkaline phosphatase, human chorionic gonadotrophin, α fetoproteinThe first two proteins are found in placenta and α fetoprotein is found in a variety of fetal tissues but not usually in the adultGerm cell neoplasms
VimentinAn intermediate filament protein of 57 kDa found mainly in cells of mesenchymal originMeningiomas, and nerve sheath tumours. Of limited use because it stains a very wide variety of cell types
S-antigenThis antigen is found in photoreceptors and pinealocytes. It is a cytosolic protein that regulates phototransduction in retinal rods. Its function in the pineal is unknownRetinoblastomas and sometimes present in tumours of the pineal gland, and medulloblastoma
PeripherinA 57 kDa intermediate filament found in the developing peripheral nervous system and also enriched in neuronal derivatives of the neural crestPeripheral neurones including enteric ganglion cells. Also expressed in neuroblastomas and ganglioneuroblastomas but does not stain chromaffin cells
Ki67The antigen is within the nucleolus during late G1, S, G2, and M phases of cell proliferationThere is a reasonable correlation with the grade of neoplasm but needs to be interpreted with caution. The Ki67 index does not always correlate with recurrence rate