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Anaplastic Oligodendroglioma


KEY FACTS

Terminology

  • Oligodendroglioma with focal or diffuse histologic features of malignancy

Imaging

  • Best diagnostic clue: Calcified frontal lobe mass involving cortex and subcortical white matter

    • Frontal lobe is most common location, followed by temporal lobe

  • Majority have nodular or clumped calcification

  • May see hemorrhage or necrosis

  • Variable enhancement

    • Anaplastic oligodendroglioma more likely to enhance than low-grade oligo

  • Neoplastic cells almost always found beyond areas of abnormal signal intensity

  • MRS and MR perfusion may help distinguish grade II from grade III oligos

Top Differential Diagnoses

  • Oligodendroglioma

  • Anaplastic astrocytoma

  • Glioblastoma multiforme

  • Cerebritis

  • Ischemia

Pathology

  • WHO grade III

  • Oligos: Better prognosis than astrocytomas of same grade

Clinical Issues

  • Headache, seizures are most common presentations

  • Occurs at all ages; mean is 49 years

  • 20-50% of oligodendrogliomas are anaplastic

  • Median survival: 4 years

  • 5-year survival: 40-45%; 10-year survival: 15%

  • 1p and 19q deletions associated with prolonged survival

Axial graphic shows a heterogeneous frontal cortical and subcortical mass with areas of necrosis and hemorrhage. Note the mass effect and infiltrative margins, typical of anaplastic grade III oligodendroglioma. These malignant gliomas have a poor prognosis.

Axial CT image in a 43-year-old man with seizures shows a calcified, cystic, and solid frontal lobe mass
. There is associated intraventricular obstructive hydrocephalus with ventricular enlargement and transependymal CSF flow (interstitial edema)
.

Axial T2 MR in the same patient shows the heterogeneously hyperintense mass
with significant mass effect and associated hydrocephalus. The T2 heterogeneity is related to cystic change
and calcification. The calcification is better seen on CT or T2* MR.

Axial T1 C+ MR in the same patient shows heterogeneous enhancement
of the mass. WHO grade III anaplastic oligodendroglioma was diagnosed at resection. Enhancement is more common in grade III than in grade II oligodendrogliomas.

TERMINOLOGY

Abbreviations

  • Anaplastic oligodendroglioma (AO), high-grade oligodendroglioma (oligo)

Definitions

  • Highly cellular, diffusely infiltrating glioma

  • Oligodendroglioma with focal or diffuse histologic features of malignancy

IMAGING

General Features

  • Best diagnostic clue

    • Calcified frontal lobe mass involving cortex and subcortical white matter (WM)

  • Location

    • Supratentorial hemispheric mass, involves cortex and subcortical WM

    • Frontal lobe most common, followed by temporal lobe

    • May involve parietal or occipital lobes

    • Often expands overlying cortex

  • Size

    • Variable

  • Morphology

    • Diffusely infiltrative mass

    • May appear discrete, but always infiltrative

    • Neoplastic cells almost always found beyond areas of abnormal signal intensity

CT Findings

  • NECT

    • Mixed density (hypodense/isodense) mass

    • Majority calcify, nodular or clumped Ca++

      • –

        May see gyriform Ca++

    • Cystic degeneration common

    • May see hemorrhage or necrosis

    • May expand, remodel, or erode calvaria

  • CECT

    • Variable enhancement

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