6. Neuro p265-283 (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
- Cortical grey matter between mass and white matter
- Displaced subarachnoid vessels
- 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.
Gangliogliomas 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 cerebri 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.
Intraventricular (2)
Tumours can arise from ventricular wall, septum pellucidum or choroid plexis.
Ventricular wall and septum pellucidum origin DDx (6)
Kids:
Ependymoma
Medulloblastoma
SEGA (Subependymal Giant Cell Astrocytoma)
Adult:
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 is much more common.
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.
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.
Intraventricular Mets (3)
Most common location of intraventricular 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).
Cerebellar Pontine Angle DDx (3)
Vestibular Schwannoma.
Meningioma.
Epidermoid
Vestibular Schwannoma (5)
75% of CPA masses.
Bilateral suggests NF2.
Enhances strongly, but more heterogenously than meningiomas.
May widen porus acousticus, resulting in a “trumpet shaped” IAC.
Meningioma (CPA) (6)
Second commonest CPA mass.
More common in women.
Can calcify, and can have dural tail (almost pathognomonic).
Extradural, so they enhance strongly.
Radiation of the head is known to cause these.
Most common location of a meningioma is over cerebral convexity.
They take up octreotide and Tc-MDP on nuclear medicine.
Epidermoid (5)
Can be congenital or acquired (after trauma, classically after LP and in the spine).
Unlike dermoids, they’re usually off the midline.
Follows CSF density and intensity on CT and MRI.
Unlike arachnoid cyst, they are bright on FLAIR (sometimes warm) and will restrict diffusion.
Dermoid cyst (6)
Less common than epidermoid (4x less).
More common in kids/young adults.
Usually midline, usually found in 3rd decade.
Contain lipoid material and are usually hypodense on CT and very bright on T1.
Associated with NF2.
Most common location is suprasellar cistern (posterior fossa is #2).
Epidermoid behaves like CSF, dermoid behaves like fat.
IAC Lipoma (3)
It can occur, and is why we look at T1 sequences when working up CPA masses.
Will fat sat out, because it’s a lipoma.
Associated with sensorineural hearing loss, as the vestibulocochlear nerve often courses through it.
Arachnoid cyst (4)
Common benign lesion that is located within the subarachnoid space, contains CSF.
Increased in frequency in mucopolysaccharidoses (as are periventricular spaces).
Dark on FLAIR like CSF. Will NOT restrict with diffusion.
Infratentorial masses DDx (7)
Atypical teratoma/rhabdoid.
Juvenile pilocytic astrocytoma.
Diffuse brain stem glioma.
Ganglioglioma
Medulloblastoma
Ependymoma
Haemangioblastoma
Atypical teratoma/Rhabdoid (4)
Highly malignant tumours, rarely occur in patients older than 6.
Average age is 2 years, can occur before 1.
Can occur in supra and infratentorial locations, most commonly in cerebellum.
Large, angry looking tumours with necrosis and heterogenous enhancement.
Juvenile Pilocystic Astrocytoma (3)
Cyst with a nodule in a kid.
WHO grade 1 but still enhance.
Located in posterior fossa or optic chiasm
Diffuse brain stem glioma (4)
Seen in kids age 3-10, most commonly in the pons, which is usually a high grade fibrillary glioma.
T2 bright with subtle or no enhancement.
4th ventricle is flattened.
Imaging features are classic, biopsy not needed.
Ganglioglioma
Can occur at any age, anwhere and look like anything.
Haemangioblastoma (4)
Cyst with a nodule in an adult.
Associated with VHL, especially if multiple.
Slow growing, indolent vascular tumours that can cause hydrocephalus from mass effect.
90% found in the cerebellum.
Supratentorial DDx (8)
Adult:
Mets (most common).
Astrocytoma
Gliomatosis cerebri.
Oligodendroglioma.
Primary CNS lymphoma.
Kids:
PXA
DNET
Desmoplastic infantile gangioganglioma/astrocytoma
Astrocytoma (8)
Most common primary brain tumour in Adults.
Several types, including
- Pilocytic astrocytoma (WHO 1)
- Diffuse astrocytoma (WHO 2)
- Anaplastic Astrocytoma (WHO 3)
- GBM (WHO 4)
Low grade tumours don’t usually ehnance (WHO 2).
Exception is that Pilocytic astroctoma often has an enhancing nodule.
GBM is the beast that cannot be stopped. Grows rapidly and restricts on diffusion.
Turcot syndrome is associated with GBM.
Gliomatosis cerebri (4)
Diffuse glioma with extensive infiltration.
Involves at least 3 lobes, often bilateral.
Usually mild blurring of the grey-white differentiation on CT, with extensive T2 hyperintensity and little mass effect on MRI.
Low grade, doesn’t typically enhance.
Primary CNS lymphoma (6)
Seen in end stage AIDS and post transplant.
EB virus plays a role.
Most common in non-hodgkin B cell lymphoma.
Classically: intensely enhancing homogemous solid mass in the periventricular region, with restricted diffusion.
Can look like anything.
Thallium positive on Spect (toxo is not).
Desmoplastic infantile ganglioglioma/astrocytoma (DIG) (5)
Large, cystic tumours that like to involve the superficial cerebral cortex and leptomeninges.
Unlike the atypical teratoma/rhabdoid, usually have OK prognosis.
ALWAYS arise in the supratentoral region, and usually involving more than one lobe (usually frontal and parietal most commonly), usually presents before first birthday.
Skull base DDx (2)
Chordoma,
Chondrosarcoma
Chordoma (4)
Locally agressive tumour originating from the notochord (midline structure relating to spinal development).
Therefore all chordomas are midline, either Clivus, vertebral bodies (especially C2) or sacrum.
Always T2 bright
Chrodosarcoma (4)
Main differential of chordoma in the clivus.
Nearly always lateral to the midline.
Also T2 bright, with “arcs and rings” matric on chondrosarcoma.
Needs CT to describe that
Dural lesion DDx (3)
Meningioma
Haemangiopericytoma
Mets
Meningioma (3)
Common, enhances homogenously.
Most common location is over the cerebral convexity, and has been known to cause hyperostosis.
Haemangiopericytoma (4)
Soft tissue sarcoma, can mimic an aggressive meningioma (because both enhance homogenously).
Can also mimic dural tail, with narrow base of dural attachment.
Won’t calcify or cause hyperostosis, but will invade the skull.
Mets (3)
Most commonly breast cancer.
80% at the grey-white junction.
More oedema than primary tumour of similar size.
Sella/parasella - Aduts DDx (5)
Pituitary adenoma,
Pituitary apoplexy,
Rathke cleft cyst,
Epidermoid,
Craniopharyngioma
Pituitary adenoma (7)
Most common tumour of the sella, 97% in adults.
If greater than 1cm, they are microadenomas.
Most functional ones secrete prolactin, especially in women.
Symptoms are easy to pick up in women (menstrual irregularity, galactorrhoea).
Men tend to present later due to more vague (decreased libido).
On MR, 80% are T1 dark and T2 bright.
Take up contrast more slowly than normal brain parenchyma.
Pituitary adenomas - trivia (4)
Microadenoma under 10mm, macro is over 10mm
Microadenomas typically form in the adenohypophysis
Prolactinoma is the most common functional type.
Typically they enhance less than normal pituitary.
Pituitary apoplexy (6)
Haemorrhage or infarction of the pituitary, usually into an enlarged gland, either from pregnancy or macroadenoma.
Associated with:
- bromocriptine (or other prolactin drugs)
- Sheehan syndrome
Will be T1 bright (adenoma is usually T1 dark).
Lack of hormones can cause hypotension.
Rathke cleft cyst (3)
Usually incidental, rarely symptomatic.
They are variable on T1 and T2, but are usually bright on T2.
Do not enhance.
Craniopharyngioma (6)
2 types:
- papillary and adamantinomatous.
Papillary type is the adult type. Solid, with no calcifications.
Recur less frequently than adamantinomatous form (because they’re encapsulated).
Strongly enhance.
Relationship to the optic chiasm is key for surgery.
Sella/parasellar - paeds DDx (2)
Craniopharyngioma,
Hypothalamic Hamartoma
Craniopharyngioma (4)
Paeds type is adamantinous.
Calcified, unlike papillary type.
Recur more than papillary.
Buzzword is “machinery oil”
Hypothalamic hamartoma (4)
Hamartoma of the tuber cinereum (part of hypothalamus located between mamillary bodies and optic chiasm).
T1 and T2 isointense. do NOT enhance.
Classic Hx of Gelastic seizures (although precocious puberty is more common)
Pineal region DDx (4)
3 main types, all of which cause “vertical gaze palsy”
Germinoma
Pineoblastoma
Pineocytoma
Germinoma (4)
Most common pineal region tumour.
Seen exclusively in boys. may cause precocious puberty, due to hCG secretion.
Mass containing fat and calcification, with variable contrast enhancement.
Heterogenous on T1 and T2 (because of mixed components).
Pineoblastoma (4)
Occurs in childhood.
Unlike pineocytoma, highly invasive.
Associated with retinoblastoma.
Heterogenous and enhance vividly.
Pineocytoma (3)
Rare in childhood.
Well circumscribed, non-invasive.
Tend to be more solid and solid components typically enhance.
Diffusion restricton DDx (5)
Supratentorial mass with restriction
- Abscess
- Lymphoma
- Rarely could be GBM or Medulloblastoma
CP angle
- Epidermoid
Temporal horns
- Herpes encephalitis
Midline crossing DDx (3)
GBM or Lymphoma.
Alternatively, radiation necrosis, big MS plaque or meningioma of the falx simulating a midline cross
Calcification DDx (2)
If in the brain, probably Oligodendroglioma.
Astrocytomas only calcify 20% of the time, but are much more common.
T1 bright DDx (5)
Tumour that has bled
- Pituitary apoplexy or haemorrhagic mets
Haemorrhagic mets
- Melanoma, Renal, Carcinoid, Choriocarcinoma, Thyroid.
Tumours with fat will also be T1 bright.
- Lipoma, Dermoid.
Melanin is also T1 bright (melanoma).
Cholesterol in a colloid cyst.
Nevoid basal cell syndrome (Gorlin)
Medulloblastoma
Turcot syndrome (2)
Medulloblastoma,
GBM
Cowdens
Lhermitte-Dulcos (dysplastic cerebellar gangliocytoma)
Tumours everywhere (5)
Likely dealing with NF2.
Not associated with neurofibromas!
MSME:
Multiple Schwannomas,
Meningiomas,
Ependymomas
Lhermitte-Dulcos (dysplastic cerebellar gangliocytoma) (5)
Very uncommon, but when you see it, think
- Cowden’s syndrome
- Associated with breast cancer, needs mammogram
Classic tiger stripe mass, typically contained on one cerebellar hemisphere (occasionally crosses the vermis).
Not cancer, but a hamartoma.
