Oligodendroglioma
Figure 1: (Top Left) This oligodendroglioma has internal coarse calcification on CT imaging that is very typical of this type of tumor. (Top Right) A coronal FLAIR image demonstrates typical fairly circumscribed permeative involvement of cortex and adjacent white matter. (Bottom) The mild hyperperfusion on this CBV image is also seen fairly often in oligodendrogliomas due to the pathologic feature of "chicken-wire" vascularity.
BASIC DESCRIPTION
- Slow-growing and infiltrating cortical/subcortical glial tumor
PATHOLOGY
- WHO grade II
- Anaplastic oligodendrogliomas are WHO grade 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 wild type, and 1p/19q codeleted
CLINICAL FEATURES
- Typically occur during fifth to sixth decades of life
- Slight male gender predilection
- Presenting symptoms: seizures, headaches, and focal neurologic deficits
- Median survival, 10 years
- Better prognosis than for astrocytomas of same WHO grade
IMAGING FEATURES
- General
- Well-marginated but infiltrating cortical/subcortical mass
- Usually supratentorial location
- Frontal lobe >> temporal, parietal, and occipital lobes
- Cystic and solid tumor components can be present in variable degrees
- Calcification present in 40% to 80%
- Usually minimal to no peritumoral edema
- Oligoastrocytomas are less common but have an appearance very similar to that of oligodendrogliomas of the same WHO grade
- CT
- Hypodense 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 imaging
- MRI
- T1WI: heterogeneous, hypointense 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
- MRS/MR perfusion: elevated choline, decreased NAA, absent lipid/lactate peak (unlike anaplastic oligodendroglioma); unique characteristic of elevated relative cerebral blood volume (rCBV) despite lower grade due to pathologic feature of “chicken-wire vascularity”
IMAGING RECOMMENDATIONS
- 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
References
Koeller KK, Rushing EJ. From the archives of the AFIP: oligodendroglioma and its variants: radiologic-pathologic correlation. Radiographics 2005;25: 1669–1688. doi.org/10.1148/rg.256055137.
Law M, Yang S, Wang H, et al. Glioma grading: sensitivity, specificity, and predictive values of perfusion MR imaging and proton MR spectroscopic imaging compared with conventional MR imaging. AJNR Am J Neuroradiol 2003;24:1989–1998.
Louis DN, Ohgaki H, Wiestler OD, et al. The 2007 WHO classification of tumours of the central nervous system. Acta Neuropathol 2007;114:547. doi.org/10.1007/s00401-007-0243-4.
Osborn AG, Salzman KL, Jhaveri MD. Diagnostic imaging (3rd ed). Elsevier, Philadelphia, PA; 2016.
Perry JR. Oligodendrogliomas: clinical and genetic correlations. Curr Opin Neurol 2001;14:705–710. doi.org/10.1097/00019052-200112000-00005.
Xu M, See SJ, Ng WH, et al. Comparison of magnetic resonance spectroscopy and perfusion-weighted imaging in presurgical grading of oligodendroglial tumors. Neurosurgery 2005;56:919–926; discussion 926.
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