Neurosurgery notes/Tumours/Gliomas, Glioneuronal Tumors, and Neuronal Tumors/Paediatrics type diffuse astrocytoma/Paediatric-type low-grade diffuse gliomas/Angiocentric glioma

Angiocentric glioma

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Paediatric-type low-grade diffuse gliomas

Definition

  • Essential:
    • Glioma with diffuse growth architecture and a focal angiocentric pattern AND
    • Monomorphic spindled cells with immunophenotypic and/or ultrastructural evidence of astrocytic and ependymal differentiation
  • Desirable:
    • Lack of anaplastic features
    • Alteration of MYB
    • DNA methylation profile aligned with diffuse glioma, MYB- or MYBL /-altered

CNS WHO grading

  • Grade 1

Numbers

  • Rare
    • 3.1% of cases of epilepsy associated tumours
  • Male: female 1:1
  • Mostly children
  • Median age of 13 year

Localization

  • Frontal or temporal lobes
  • Increasing more found thalamic and increasingly brainstem

Origin

  • Maldevelopment or neoplastic process from bipolar radial glial that span the neuroepithelium during embryogenesis
    • Share ependymoglial traits and capable of generating ependymocytes

Pathology

Microscopic

  • A focal tumour
  • Infiltrative margins composed of bipolar glial cells orientated around a cortical blood vessel
  • Monomorphic, bipolar spindled cells orientated around a cortical blood vessel in a single or multilayer sleeve
  • Rare mitosis (Ki-67<1%)
A close-up of a microscope AI-generated content may be incorrect.
Pseudorossettes
A close-up of a microscope AI-generated content may be incorrect.
Perivascular pseudorossettes

Immunophenotype

  • +
    • GFAP
    • EMA
  • -
    • Neuronal antigen (synaptophysin, chromogranin-A and NeuN),
    • R132H-mutant IDH1

Genetic

  • MYB-QKI gene fusion
    • Results in → Deletion of intervening domains causing
      • Deletion of a negative regulatory domain in MYB,
      • Functional deletion of the tumour suppressor OKI,
      • Enhancer translocation forcing expression of the constitutively active MYB::QKI allele → driving MAPK signalling
    • Near all have this
  • MYB-ESR1 fusion
    • Rare
  • Do not have: IDH1, IDH2, and BRAF V600 mutations
  • Might have association with
    • NF 1
    • Koolen-de Vries syndrome

Clinical features

  • Chronic and intractable partial epilepsy

Radiology

  • Superficial, well circumscribed
  • The tumours are hyperintense on T2w/ FLAIR
  • Non-enhancing with a rim-like T1 hyperintensity surrounding the tumour
  • Stalk-like components extending towards the lateral ventricle
  • Calcification
    • Sometime present but is not characteristic
  • MR spectroscopy
    • Elevated
      • Myo-inositol and glycine
      • Choline
    • Decreased NAA
  • T2w (A, B) shows a cortical/subcortical lesion in the left middle frontal gyrus without restricted diffusion (C) or enhancement on T1w-CE (D).
  • No blood product present (SWI not shown)
`쬐0
An 8-year-old boy presenting with recurrent seizures with a focal semiology and behavioural changes. Methylation class low grade glioma MYB/MYBL1. QKI-MYB fusion was detected using the RNA fusion panel.
A close-up of a brain scan AI-generated content may be incorrect.
T1 w/ contrast
A close-up of a brain scan AI-generated content may be incorrect.
Flair

Spread

  • Infiltrative → trapping local neurons
    • Gray-white matter boundary may be blurred

Outcome

  • Show stability on radiological surveillance
  • Excision is curative
    • Uncommon recurrence