IDH-1 polymorphisms in pilocytic astrocytomas

Ann Diagn Pathol. 2019 Dec:43:151411. doi: 10.1016/j.anndiagpath.2019.151411. Epub 2019 Oct 23.


As of 2016, isocitrate dehydrogenase (IDH)-1 and IDH-2 mutations are part of the definition of an oligodendroglioma and may be seen in a significant subset of grade II-IV fibrillary astrocytomas. Reports of IDH-1 and IDH-2 alterations in pilocytic astrocytomas have been rare. This study reports two cases of pilocytic astrocytomas which harbored IDH-1 polymorphisms (G105G) (c.315C > T) discovered on polymerase chain reaction (PCR) testing and sequencing. The first was encountered in a 21-year-old male with a right orbital frontal pole mass. The second occurred in a 19-year-old female with a right frontal tumor. Neither tumor stained with antibody to IDH-1 (R132H). No BRAF V600E immunostaining, minimal p53 staining (<5%) and no loss of ATRX staining was noted in both cases. The significance of the IDH-1 findings at this juncture is uncertain. Misdiagnosis of the tumor as a fibrillary astrocytoma or oligodendroglioma due to the presence of an IDH alteration should be avoided.

Keywords: Glioma; IDH-1 mutation; IDH-1 polymorphism; IDH-2 mutation; Pilocytic astrocytoma.

Publication types

  • Case Reports

MeSH terms

  • Astrocytoma / genetics*
  • Astrocytoma / pathology
  • Astrocytoma / surgery
  • Central Nervous System Neoplasms / diagnostic imaging
  • Central Nervous System Neoplasms / pathology*
  • Central Nervous System Neoplasms / surgery
  • Diagnostic Errors
  • Female
  • Humans
  • Isocitrate Dehydrogenase / genetics*
  • Male
  • Mutation
  • Oligodendroglioma / genetics*
  • Oligodendroglioma / pathology
  • Oligodendroglioma / surgery
  • Polymorphism, Genetic / genetics
  • Treatment Outcome
  • Young Adult


  • Isocitrate Dehydrogenase
  • IDH1 protein, human