CNS tumor
Diffuse astrocytic and oligodendroglial tumors
Gemistocytic astrocytoma, IDH-mutant



Topic Completed: 1 February 2018

Revised: 2 January 2019, last major update February 2018

Copyright: (c) 2002-2018, PathologyOutlines.com, Inc.

PubMed Search: Gemistocytic astrocytoma IDH-mutant


Eman Abdelzaher, M.D., Ph.D.
Page views in 2018: 2,059
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Cite this page: Abdelzaher E. Gemistocytic astrocytoma IDH-mutant. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/cnstumorgemistocyticastrocytomaIDHmut.html. Accessed October 21st, 2019.
Definition / general
  • Variant of IDH-mutant diffuse astrocytoma characterized by the presence of a recognizable population of neoplastic gemistocytes (> 20%)
Epidemiology
  • Accounts for approximately 10% of all WHO grade II diffuse astrocytomas
  • Age: fourth decade
  • Appears more frequently in men
Sites
  • Any region of the CNS
  • Most commonly affects the frontal and temporal lobes
Grading
  • 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
Microscopic (histologic) images

Images hosted on other servers:

Presence of gemistocytes

Dense eosinophilic cytoplasm

Uniform population of large cells

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
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