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

(Left) 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. (Right) 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) ﬊.

(Left) 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.

(Right) 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.

Cysts, and Disorders

Brain: Pathology-Based Diagnoses: Neoplasms,

135