Skip to content

Oligodendroglioma

Summary

fleuron

  • Oligodendroglioma is a slow-growing, diffusely infiltrating glial tumour of the central nervous system
  • Typically affects adults in their 4th-5th decades of life
  • Characterised by classic "fried egg" appearance histologically and 1p/19q co-deletion genetically

Pathophysiology

  • Typically occurs in the cerebral hemispheres, particularly the frontal lobes
  • Molecular markers include 1p and 19q co-deletion and IDH1/2 mutuation
  • Typical findings of histopathological include "fried egg" oligodendrocytes, chicken-wire neovascularisation and microcalcification

Demographics

  • Accounts for approximately 5-20% of all gliomas and 5-10% of all intracranial tumours
  • Peak incidence in 4th-5th decades of life
  • Slight male predominance (M:F ratio 1.1-2:1)

Diagnosis

  • Clinical presentation:
    • Seizures (50-80% of cases)
    • Headaches
    • Focal neurological deficits
    • Cognitive changes

Imaging

  • CT:
    • Hypoattenuating cortical/subcortical mass
    • Calcifications in 50-90% of cases
    • May cause remodelling of the overlying skull (representing slow growth)
  • MRI:
    • ++T2/FLAIR++ hyperintense
    • T1 hypointense to isointense
    • T1+C Minimal to moderate enhancement with contrast
    • SWI Hypointensity/blooming due to calcification (or, more rarely, haemorrhage)
  • Advanced imaging:
    • MR spectroscopy: elevated Cho/NAA ratio, presence of lactate/lipid peak
    • Perfusion imaging: CBV may be elevated even in grade 2 lesions

panels-1

  • A 40-year-old patient presented after a tonic-clonic seizure.
  • MRI showed a relatively well-demarcated tumour in the left frontal lobe that involved cortex.
  • Phase data from SWI showed diamagnetic susceptibility artefact consistent with dystrophic calcification.
  • There was punctate enhancement and elevated CBV (ratio of 2.5 relative contralatera normal appearing brain tissue).
  • MRS showed elevated choline and reduced NAA (indicating the replacement of normal neurons with mitotically active cells).

Treatment

  • Maximal safe surgical resection is the initial treatment of choice
  • Adjuvant therapy based on grade and molecular profile:
    • Grade II: observation or radiotherapy ± chemotherapy
    • Grade III (anaplastic): radiotherapy + chemotherapy (typically PCV or temozolomide)
  • Chemotherapy:
    • PCV (procarbazine, lomustine, vincristine) regimen
    • Temozolomide as an alternative
  • Radiotherapy:
    • Typically 54-60 Gy in 1.8-2 Gy fractions
  • Prognosis:
    • Generally better than astrocytomas
    • 1p/19q co-deletion and IDH mutation associated with improved survival
    • 5-year survival rates: 50-80% for grade II, 30-60% for grade III

Differential diagnosis

Differential Diagnosis Differentiating Feature
Astrocytoma T2/FLAIR mismatch sign (bright T2 but suppressed on FLAIR) favours astrocytoma; less well-defined margins; calcification rare
Dysembryoplastic neuroepithelial tumour (DNET) "Bubbly" multinodular cortical architecture; no enhancement; typically in younger patients
Ganglioglioma Cystic lesion with mural nodule; mixed cystic-solid architecture; calcification less prominent
Glioblastoma Central necrosis; ring enhancement; elevated rCBV; marked DWI restriction