title: Posterior fossa and spinal gangliogliomas form two distinct clinicopathologic and molecular subgroups.
abstract: BACKGROUND
  Gangliogliomas are low-grade glioneuronal tumors of the central nervous system and the commonest cause of chronic intractable epilepsy. Most gangliogliomas (>70%) arise in the temporal lobe, and infratentorial tumors account for less than 10%. Posterior fossa gangliogliomas can have the features of a classic supratentorial tumor or a pilocytic astrocytoma with focal gangliocytic differentiation, and this observation led to the hypothesis tested in this study - gangliogliomas of the posterior fossa and spinal cord consist of two morphologic types that can be distinguished by specific genetic alterations.
  
  
  RESULTS
  Histological review of 27 pediatric gangliogliomas from the posterior fossa and spinal cord indicated that they could be readily placed into two groups: classic gangliogliomas (group I; n = 16) and tumors that appeared largely as a pilocytic astrocytoma, but with foci of gangliocytic differentiation (group II; n = 11). Detailed radiological review, which was blind to morphologic assignment, identified a triad of features, hemorrhage, midline location, and the presence of cysts or necrosis, that distinguished the two morphological groups with a sensitivity of 91% and specificity of 100%. Molecular genetic analysis revealed BRAF duplication and a KIAA1549-BRAF fusion gene in 82% of group II tumors, but in none of the group I tumors, and a BRAF:p.V600E mutation in 43% of group I tumors, but in none of the group II tumors.
  
  
  CONCLUSIONS
  Our study provides support for a classification that would divide infratentorial gangliogliomas into two categories, (classic) gangliogliomas and pilocytic astrocytomas with gangliocytic differentiation, which have distinct morphological, radiological, and molecular characteristics.
authors: Kirti
authors: K
authors: Gupta
authors: Wilda
authors: W
authors: Orisme
authors: Julie H
authors: JH
authors: Harreld
authors: Ibrahim
authors: I
authors: Qaddoumi
authors: James D
authors: JD
authors: Dalton
authors: Chandanamali
authors: C
authors: Punchihewa
authors: Racquel
authors: R
authors: Collins-Underwood
authors: Thomas
authors: T
authors: Robertson
authors: Ruth G
authors: RG
authors: Tatevossian
authors: Department of Pathology, St, Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA. David.Ellison@stjude.org.
authors: David W
authors: DW
authors: Ellison
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D018303:Ganglioglioma / Q000145:classification / Q000235:genetics / Q000473:pathology; D005820:Genetic Testing; D006801:Humans; D007223:Infant; D015192:Infratentorial Neoplasms / Q000145:classification / Q000235:genetics / Q000473:pathology; D008297:Male; D009154:Mutation / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics*; D013120:Spinal Cord Neoplasms / Q000145:classification / Q000235:genetics / Q000473:pathology; D055815:Young Adult
chemical_list: D011993:Recombinant Fusion Proteins; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf