CNS tumor

Diffuse astrocytic and oligodendroglial tumors

Gemistocytic astrocytoma IDH mutant

Topic Completed: 1 February 2018

Minor changes: 4 September 2020

Copyright: 2002-2021,, Inc.

PubMed Search: Gemistocytic astrocytoma IDH-mutant

Eman Abdelzaher, M.D., Ph.D.
Page views in 2020: 4,691
Page views in 2021 to date: 4,787
Cite this page: Abdelzaher E. Gemistocytic astrocytoma IDH mutant. website. Accessed November 27th, 2021.
Definition / general
  • Variant of IDH mutant diffuse astrocytoma characterized by the presence of a recognizable population of neoplastic gemistocytes (> 20%)
  • Accounts for approximately 10% of all WHO grade II diffuse astrocytomas
  • Age: fourth decade
  • Appears more frequently in men
  • Any region of the CNS
  • Most commonly affects the frontal and temporal lobes
  • WHO grade II
Prognostic factors
  • Gemistocytic astrocytoma has been associated with early progression and less favorable outcome
  • However, it remains to be determined whether the prognosis of IDH mutant gemistocytic astrocytoma differs significantly from that of IDH mutant diffuse astrocytoma
Gross description
  • Similar to other low grade diffuse gliomas
  • May have single, large, smooth walled cyst
Microscopic (histologic) description
  • Conspicuous proportion of neoplastic gemistocytes (> 20%)
  • Neoplastic gemistocytes are angular shaped with abundant, glassy, eosinophilic cytoplasm and eccentric nuclei with distinct nucleoli
  • There is a coarse fibrillary background formed by stout cytoplasmic processes
  • Intermingled small cell component: small tumor cells with dark nuclei and scanty cytoplasm; constitutes the proliferating component with higher Ki67 index compared to gemistocytic cells
  • Perivascular lymphocyte cuffing is common
  • Rare or no mitoses
Positive stains
  • GFAP: consistently expressed in neoplastic gemistocytes
  • IDH1
  • p53: frequently seen in small and gemistocytic tumor cells
  • Ki67: higher proliferation index in the small cell component compared with neoplastic gemistocytes
Molecular / cytogenetics description
  • Mutations in IDH genes
  • High frequency of p53 mutations
Differential diagnosis
Back to top
Image 01 Image 02