6. Neuro (Brain - Tumours) Flashcards
Multiple masses DDx (3)
Multifocal primary from seeding.
Mets.
Syndromes (e.g. NF2)
Tumour vs mimic (3)
Mimics include abscess, infarct, MS plaque.
Incomplete ring enhancement - think MS plaque.
Diffusion restricution is either lymphoma or stroke or abscess. Lymphoma will enhance homogenously
Intra-axial vs extra-axial (6)
Signs of extra-axial location:
- CSF cleft
- Displaced subarachnoid vessels
- Cortical grey matter between mass and white matter
- Displaced and expanded subarachnoid spaces
- Broad dural base
- Bony reaction
Why enhancement? (5)
Things don’t enhance because of the blood brain barrier.
When they do enhance, it’s because they are extra-axial OR because they have compromised the blood brain barrier.
Extra axial things, e.g. meningioma, will enhance. High grade tumours and infections enhance.
Low grade tumours aren’t bad enough to damage the blood brain barrier, so they don’t enhance.
Gangliomas and Pilocytic astrocytomas are the exceptions, low grade tumours that enhance
Multiple masses (2)
In adults or kids, multiple masses means likely mets or infection.
Differentiating is done on diffusion (infection will restrict).
Mets - trivia (8)
Commonest CNS met in kid is neuroblastoma (bones, dura, orbit - not brain).
Most common location for mets is supratentorial at the grey-white junction (much blood flow and abrupt vessel caliber change). Also see haematogenois spread of infection go there too
Most common morphology is round/spherical
Mets can be singular 50% of the time. Solitary mass in adult is more likely met than primary CNS neoplasm.
MRCT for bleeding mets (Melanoma, Renal, Carcinoid, Choriocarcinoma, Thyroid)
Mets usually have more surrounding oedema than similar sized CNS primary.
Next step in an adult is look for primary (lung, breast, colon)
Multifocal brain tumours (3)
Lymphoma, multicentric GBM, Gliomatosis gerebri like to be multifocal.
Medulloblastoma, Ependymoma, GBM, oligodendrogliomas can be multifocal from seeding.
Syndromes: tumours with syndromes are more likely to be multifocal
Tumour associated syndromes (4)
NF1 - Optic gliomas, Astrocytomas
NF2 - Multiple schwannomas, meningiomas, ependymomas
Tuberous sclerosis - Subependymal tubers, IV giant cell astrocytomas
VHL - haemangioblastomas
Cortical based lesions DDx (8)
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
Oligodendroglioma (4)
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.
Ganglioglioma (3)
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
DNET (Dysembryonic Neuroepithelial Tumour) (5)
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”
Pleomorphic Xanthoastrocytoma (PXA) (6)
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.
Interventricular (2)
Tumours can arise from ventricular wall, septum pellucidum or choroid plexis.
Ventricular wall and septum pellucidum origin DDx (6)
Ependymoma (kids)
Medulloblastoma (kids)
SEGA (Subependymal Giant Cell Astrocytoma) (kids)
Subependymoma (adult)
Central neurocytoma (young adult)
Ependymoma (7)
Bimodal age distribution, large peak around 6YO, smaller peak at 30.
2 kinds:
4th ventricle
- 70%
- frequent extension into the foramen of Luschka and Magendie.
- “Plastic tumour” or “toothpaste tumour” because they squeeze out of the 4th ventricle
Parenchymal supratentorial (30%)
- Usually big (>4cm) at presentation
Medulloblastoma (7)
Classic medulloblastoma, type of PNET.
Paediatric tumour occuring mostly before age 10 (second smaller peak 20-40).
Arise from cerebellar vermis, projecting into the 4th ventricle. Met via CSF pathways.
Heterogenous on T1 and T2, with homogenous enhancement.
Much more common than ependymomas.
They’re hypercellular and restrict diffusion.
Calcify 20%, less than ependymomas.
Like to “drop met” into CSF.
“Zuckerguss” - sugar icing as seen on post contrast imaging of the brain and cord.
Associated with basal cell naevus syndrome and Turcots syndrome
Gorlin syndrome (6)
Medulloblastoma with dural calcifications.
They also get skin BCCs after radiation and have odontogenic cysts.
Pre-op imaging of the entire spinal axis should be done with posterior fossa neoplasm, especially if meduloblastoma or ependymoma.
Evidence of tumour spread is a predictor of outcome
Medulloblastoma vs Ependymoma (7)
More common vs less commoin
Originate from vermis/FLOOR of 4th ventricle vs originate from ROOF of 4th ventricle
Can project into 4th ventricle, do NOT usually extend into basal cisterns vs Can extend into basal cisterns (toothpaste) and push through foramina of Luschka and Magendie
Homogenous vs heterogenous enhancement.
Calcifies less (20%) vs more (50%).
Linear “icing sugar” like enhancement of the brain surface
SubEpendymal Giant cell Astrocytoma (SEGA) (4)
Associated with tuberous sclerosis.
Associated with renal AML or seizures/developmental delay.
Seen in kids, average age 11.
Arises from lateral wall of ventricle, near the foramen of monro, often causing hydrocephalus.
Homogenous enhancement.
SEGA vs Subependymal Nodule (4)
SEN will stay stable in size, the SEGA will grow.
SEGA found in lateral ventricle, near the foramen of Monro, SEN can occur anywhere along the ventricle.
SEN is much more common.
Both can calcify.
Enhancing, partly calcified lesion at the foramen of Monro, bigger than 5mm, is a SEGA.
Subependymoma (4)
Found in adults.
Well circumscribed intraventricular masses, most commonly at the foramen of monro and 4th ventricle.
Can cause hydrocephalus.
Typically don’t enhance. T2 bright like most tumours
Central neurocytoma (3)
Most common intraventricular mass in an adult (aged 20-40).
“swiss cheese” due to numerous cystic spaces on T2.
Calcify a lot
Choroid plexus origin tumours DDx (5)
Choroid plexus papilloma/carcinoma
Xanthogranuloma.
Mets.
Colloid cyst.
Meningioma
Choroid plexus papilloma/carcinoma (4)
85% occur in kids, commonly before age 5.
Make up 15% of tumours in kids under 1.
Intraventricular mass, often making CSF, so causes hydrocephalus.
Brain tumours are usually supratentorial in adults and posterior fossa in kids. This tumour is an exception.
Choroid plexus papilloma/carcinoma trivia (6)
Adults: 4th ventricle. Kids: lateral ventricle, usually trigone.
Carcinoma type is only seen in kids and therefore only in the lateral ventricle/trigone.
Carcinoma associated with Li-Fraumeni syndrome (p53 mutation)
Angiography may show enlarged choroidal arteries which shunt blood to the tumour.
Carcinoma type looks similar (unless invading the parenchyma) and almost exclusively seen in kids.
Usually solitary, can rarely have CSF dissemination.
Xanthogranuloma (3)
Benign choroid plexus mass.
Seen in 7% of population.
They restrict diffusion.
Mets (3)
Most common location of intraventriculr mets is trigone of lateral ventricles, because of blood supply to choroid plexus.
Most common primary is controversial, either lung or renal.
Colloid cyst (5)
Almost exclusively seen in anterior part of the 3rd venticle, behind the foramen of Monro.
Can cause sudden death via acute hydrocephalus.
Varied appearance, depends what they’re made of.
If cholesterol, T1 bright and T2 dark.
If not, they can be T2 bright.
Round, well circumscribed mass in the anterior 3rd ventricle. Can be fairly dense on CT.
Meningioma (2)
Can occur in an intraventricular location, most commonly (80%), at the trigone of the lateral ventricles (slightly more on the left).