Neurosurgery notes/Tumours/Gliomas, Glioneuronal Tumors, and Neuronal Tumors/Adult type diffuse astrocytoma/Low grade gliomas/Astrocytoma, IDH mutant/Grade 3 Astrocytoma IDH mutant

Grade 3 Astrocytoma IDH mutant

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Astrocytoma, IDH mutant

Aka

  • Anaplastic astrocytoma

Definition

  • A diffusely infiltrative astrocytic glioma with an IDH1 or IDH2 mutation AND
  • Exhibits focal or dispersed anaplasia AND
  • Displays significant mitotic activity AND
    • Absent
      • Microvascular proliferation
      • Necrosis
      • Homozygous deletions of CDKN2A and/or CDKN2B

Can arise from

  • Grade 2 diffuse astrocytoma or
  • From a precursor cell directly

Numbers

  • 38yrs

Localisation

  • Frontal lobe

Imaging

  • MRI
      • 54-year-old man
      • WHO 2016:
        • Grade III anaplastic astrocytoma, IDHmut.
      • WHO 2021 integrated diagnosis
        • (Molecular: IDHmut, 1p/19q retained, no CDKN2A deletion): Astrocytoma, IDH-mutant, CNS WHO grade 3.
      • The left insular and temporal lobe tumour demonstrates homogenous high signal on T2w (D) and partial suppression on FLAIR (E) with faint enhancement on T1w-CE (F).
      notion image

Pathology

Macroscopic

Anaplastic astrocytoma in the right frontotemporal region. Note the ill-defined borders with the adjacent brain structures and focal cysts.
Anaplastic astrocytoma in the right frontotemporal region. Note the ill-defined borders with the adjacent brain structures and focal cysts.
Frontotemporal anaplastic astrocytoma containing a large cyst but no macroscopically discernible necrosis.
Frontotemporal anaplastic astrocytoma containing a large cyst but no macroscopically discernible necrosis.
Anaplastic astrocytoma with diffuse, bilateral infiltration of the corpus callosum, the caudate nucleus, and the fornices. The fornices are grossly enlarged and show petechial haemorrhages.
Anaplastic astrocytoma with diffuse, bilateral infiltration of the corpus callosum, the caudate nucleus, and the fornices. The fornices are grossly enlarged and show petechial haemorrhages.

Microscopic

Marked nuclear pleomorphism. Note the atypical mitosis in the centre.
Marked nuclear pleomorphism. Note the atypical mitosis in the centre.
Hypercellularity and hyperchromatic, irregular, so-called naked nuclei appearing within a fibrillary background. Two mitotic figures are present.
Hypercellularity and hyperchromatic, irregular, so-called naked nuclei appearing within a fibrillary background. Two mitotic figures are present.

Outcomes

  • Median survival of 3-5 years
  • Better outcomes with IDH mutation
  • Poor outcomes with
    • 7q gain
    • 10q loss
    • EGFR amplification