Cortical based lesions

Question 1

Cortical based lesions DDx (8)

Answer 1

Most intra-axial tumours are located in the white matter.
When a tumour spreads to, or is primarily located in the grey matter, there is a shorter DDx.
Cortical tumours or mets often have very little oedema, so can be occult without IV contrast.
PDOG
- Pleomorphic Xanthoastrocytoma
- Dysembryonic Neuroepithelial Tumour
- Oligodendrioglioma
- Ganglioglioma

Question 1

Oligodendroglioma (4)

Answer 1

Adult 40-50s.
Calcifies in 90%. Most common in frontal lobe.
“Expands the cortex” - cortical infiltration and marked thickening.
1p/19q deletion associated with better outcomes.

Question 2

Ganglioglioma (3)

Answer 2

Can occur at any age with any appearance.
Classic scenario: 13YO with seizures, temporal lobe mass that’s cystic and solid with focal calcifications.
May have overlying bony remodelling

Question 3

DNET (Dysembryonic Neuroepithelial Tumour) (5)

Answer 3

Kid with drug resistant seizures.
Mass will always be in temporal lobe.
Focal cortical dysplasia seen in 80%.
Hypodense on CT and little surrounding oedema on MRI.
High T2 signal “bubbly lesion”

Question 4

Pleomorphic Xanthoastrocytoma (PXA) (6)

Answer 4

Kid, 10-20.
Superficial tumour, always supratentorial and usually involves temporal lobe.
Often a cyst with a nodule.
No peritumeral T2 signal.
Frequently invades the leptomeninges.
Looks like desmoplastic infantile ganglioma, but not an infant.