title: PIK3CA mutation in a mixed dysembryoplastic neuroepithelial tumor and rosette forming glioneuronal tumor, a case report and literature review.
abstract: BACKGROUND
  Rosette forming glioneuronal tumors are rare, World Health Organization (WHO) grade I novel tumors frequently affecting the fourth ventricle or posterior fossa with typical neuronal pseudorosettes. RGNTs have been described as possessing additional histologic features of DNETs or pilocytic astrocytomas. Activating PIK3CA mutations have been identified as recurring genetic event in RGNTs.
  
  
  METHODS
  We report a 35year old man who presented with binocular diplopia, headache, and was found to have a third ventricle tumor. Tumor pathology and oncogene evaluation were conducted.
  
  
  RESULTS
  The tumor demonstrated histologic features consistent with mixed RGNT/DNET. Genetic studies revealed a PIK3CA mutation in exon 9 (E545K, C. 1633G>A) without IDH1, p53, 1p19q chromosomal co-deletion, or BRAF mutations. A literature search revealed six cases of PIK3CA mutations in RGNTs and seven cases of mixed RGNT/DNET. No cases of mixed RGNT/DNET with a PIK3CA mutation have been described.
  
  
  CONCLUSIONS
  This is the first documented case of an RGNT/DNET with an activating PIK3CA mutation. The presence of a PIK3CA mutation aids histologic classification in the setting of mixed histology, and may have implications for targeting the PI3K/AKT/mTOR pathway in this tumor type.
authors.affiliation: Walter Reed National Military Medical Center, Department of Neurology, United States. Electronic address: p.g.eye88@gmail.com.
authors.forename: Philip George
authors.initials: PG
authors.lastname: Eye
authors.affiliation: Walter Reed National Military Medical Center, Department of Neurosurgery, United States.
authors.forename: Laurence
authors.initials: L
authors.lastname: Davidson
authors.affiliation: Walter Reed National Military Medical Center, Department of Pathology and Laboratory Medicine, United States.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Malafronte
authors.affiliation: Walter Reed National Military Medical Center, Darnell Medical Library, United States.
authors.forename: Sarah
authors.initials: S
authors.lastname: Cantrell
authors.affiliation: Walter Reed National Military Medical Center, Department of Neurology, United States.
authors.forename: Brett J
authors.initials: BJ
authors.lastname: Theeler
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D058534:Class I Phosphatidylinositol 3-Kinases; D006801:Humans; D008297:Male; D009154:Mutation; D018302:Neoplasms, Neuroepithelial / Q000000981:diagnostic imaging / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics*
chemical_list: D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human
keywords: Case report; Dysembryoplastic neuroepithelial tumor; PIK3CA; Rosette forming glioneuronal tumor