title: Genetic differences between neurocytoma and dysembryoplastic neuroepithelial tumor and oligodendroglial tumors.
abstract: OBJECTIVE
  Because of their histological similarities, it is occasionally difficult to differentiate neurocytoma and dysembryoplastic neuroepithelial tumor (DNT) from oligodendroglial tumors. This study was conducted to investigate genetic differences among these tumor types in terms of loss of heterozygosity on chromosomes 1p and 19q, and p53 gene mutation.
  
  
  METHODS
  A total of 24 tumors were analyzed, consisting of eight central neurocytomas, three DNTs, seven oligodendrogliomas, four oligoastrocytomas, and two undetermined extraventricular tumors with neurocytoma features (ETNFs). Allelic loss was determined using microsatellite markers that cover the common deletions on chromosomes 1p and 19q in oligodendrogliomas. A p53 gene mutation was identified using polymerase chain reaction-single-strand conformation polymorphism analysis and subsequent direct sequencing. Immunohistochemical studies with synaptophysin and electron microscopy investigations were also conducted. Allelic loss on 1p and 19q was detected in six oligodendrogliomas (86%) and in three oligoastrocytomas (75%), but in none of the central neurocytomas or DNTs. A p53 missense mutation was detected at codon 161 (GCC-->ACC, Ala-->Thr) in only one oligoastrocytoma without allelic loss. Synaptophysin was expressed in all central neurocytomas and DNTs, in three oligodendrogliomas (43%), and in three oligoastrocytomas (75%). Of the ETNFs, one demonstrated synaptophysin expression and neural ultrastructures but lacked genetic alterations, whereas the other showed allelic loss on 1p and 19q but was negative immunohistochemically and ultrastructurally. The former was diagnosed as a potential intraparenchymal neurocytoma and the latter as an oligodendroglioma.
  
  
  CONCLUSIONS
  Despite histological similarities, central neurocytomas and DNTs are genetically distinct from oligodendroglial tumors. Examination for allelic loss on 1p and 19q and for p53 mutation can be useful for making this distinction.
authors.affiliation: Department of Neurosurgery, Division of Neuroscience, Graduate School of Medical Science, Kanazawa University, Kanazawa, Japan. fujisawa@ns.m.kanazawa-u.ac.jp
authors.forename: Hironori
authors.initials: H
authors.lastname: Fujisawa
authors.forename: Kohei
authors.initials: K
authors.lastname: Marukawa
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Tohma
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Uchiyama
authors.forename: Osamu
authors.initials: O
authors.lastname: Tachibana
authors.forename: Junkoh
authors.initials: J
authors.lastname: Yamashita
mesh_terms: D000293:Adolescent; D000328:Adult; D001932:Brain Neoplasms / Q000737:chemistry / Q000175:diagnosis / Q000235:genetics*; D002878:Chromosomes, Human, Pair 1; D002888:Chromosomes, Human, Pair 19; D018699:Coated Vesicles / Q000648:ultrastructure; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009154:Mutation; D018302:Neoplasms, Neuroepithelial / Q000737:chemistry / Q000175:diagnosis* / Q000473:pathology; D018306:Neurocytoma / Q000737:chemistry / Q000175:diagnosis / Q000235:genetics*; D009837:Oligodendroglioma / Q000737:chemistry / Q000175:diagnosis / Q000235:genetics*; D016708:Synaptophysin / Q000032:analysis; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
chemical_list: D016708:Synaptophysin; D016159:Tumor Suppressor Protein p53