title: MR imaging findings of extraventricular neurocytoma: a series of ten patients confirmed by immunohistochemistry of IDH1 gene mutation.
abstract: BACKGROUND
  Extraventricular neurocytomas (EVNs) are rare neuronal tumors included as neoplasms in the 2007 World Health Organization (WHO) classification of tumors of the CNS. Although a few case reports describing EVNs have been published, a systematic analysis of MR imaging findings of EVN has not been reported. Furthermore, imaging findings of IDH1 mutation-negative EVNs have not yet been reported. The aim of our study is to describe the MR imaging findings of IDH1 mutation-negative EVNs.
  
  
  METHODS
  MR images of ten patients with pathologically confirmed IDH1 mutation-negative EVNs were retrospectively reviewed. Conventional MR imaging of ten EVNs were reviewed with emphasis on the location, signal intensities, patterns, and grades of enhancement as well as the presence/grade of peritumoral edema, intratumoral cyst, hemorrhage, and calcification. The study also reviewed the results of DWI (b = 1,000 s/mm(2), n = 7).
  
  
  RESULTS
  Seven EVN cases were located in the cerebral hemisphere, and the remaining cases were in the cerebellum and thalamus. Of those in the cerebral hemisphere, five were cortically based tumors. The tumors showed no or mild peritumoral edema. Eight tumors were enhanced on the postcontrast T1WIs. An intratumoral cyst, hemorrhage, and calcification were detected in four, one, and two cases, respectively. On DWI, only one case showed a lower ADC value than the brain parenchyma.
  
  
  CONCLUSIONS
  EVNs are usually cortically based infiltrative hemispheric tumors with contrast enhancement, higher ADC value, and sometimes small cystic component, but hardly show peritumoral edema or intratumoral hemorrhage. The differential diagnosis of these findings includes low-grade glioneuronal tumors and low-grade gliomas.
authors.affiliation: Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Republic of Korea.
authors.forename: Kyung Sik
authors.initials: KS
authors.lastname: Yi
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Sohn
authors.forename: Tae Jin
authors.initials: TJ
authors.lastname: Yun
authors.forename: Seung Hong
authors.initials: SH
authors.lastname: Choi
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Moon Hee
authors.initials: MH
authors.lastname: Han
authors.forename: Chul-Kee
authors.initials: CK
authors.lastname: Park
authors.forename: Sung-Hye
authors.initials: SH
authors.lastname: Park
authors.forename: Kee-Hyun
authors.initials: KH
authors.lastname: Chang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000473:pathology; D001932:Brain Neoplasms / Q000175:diagnosis / Q000473:pathology*; D002648:Child; D005260:Female; D005910:Glioma / Q000175:diagnosis / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007521:Isocitrate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009154:Mutation; D060787:Neoplasm Grading; D018306:Neurocytoma / Q000175:diagnosis / Q000473:pathology*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human