Last Updated: March 27, 2020
- Slow-growing and infiltrating cortical/subcortical glial tumor
- WHO grade II
- Anaplastic oligodendrogliomas (AO) are WHO III
- Arises from malignant transformation of mature oligodendrocytes or glial precursor cells
- calcification and cystic degeneration common
- “Fried egg” microscopic appearance due to rounded nuclei and clear cytoplasm
- Genetics by WHO 2016 Classification: IDH-mutant, ATRX-wildtype and 1p/19q-codeleted
- Typically occur during 5th to 6th decades
- Slight male gender predilection
- Presenting symptoms: seizures, headaches, and focal neurologic deficits
- Median survival 10 years
- Better prognosis than astrocytomas of same WHO grade
- Well-marginated but infiltrating cortical/subcortical mass
- Usually supratentorial location
- Frontal lobe >> temporal, parietal, and occipital lobes
- Cystic and solid tumor components may be present in variable degrees
- Calcification present in 40-80%
- Usually minimal to no peritumoral edema
- Oligoastrocytomas are less common but have a very similar appearance to oligodendrogliomas of the same WHO grade
- Hypo- to isodense supratentorial mass involving the cortex and subcortical white matter
- Hyperdense foci if hemorrhage or calcification is present
- Variable enhancement on contrast-enhanced CT
- T1WI: heterogeneous, hypo- to isointense relative to gray matter; ± adjacent cortical involvement with expansion
- T2WI: heterogeneously hyperintense due to hemorrhage, cystic degeneration, and calcification
- FLAIR: heterogeneously hyperintense, minimal peritumoral edema
- T2*/GRE/SWI: Black signal blooming secondary to calcification and/or hemosiderin deposition from blood products
- DWI: usually does not show restricted diffusion
- T1WI+C: heterogeneous enhancement; new enhancement in WHO II tumors suggests malignant degeneration to anaplastic oligodendroglioma
- MR Spectroscopy (MRS)/MR perfusion: elevated choline, decreased NAA, absent lipid/lactate peak (unlike anaplastic oligodendroglioma); unique characteristic of elevated relative cerebral blood volume (rCBV) in spite of lower grade due to pathologic feature of “chicken-wire vascularity”
- MRI with contrast including T2*/GRE/SWI, CT for demonstration of calcification
For more information, please see the corresponding chapter in Radiopaedia.
Contributor: Rachel Seltman, MD
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Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, Burger PC, Jouvet A, et al. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol 2007;114:547.
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