Brain tumours Flashcards
List the intraventricular brain tumors
- Ependymoma (children, toothpaste lesion)
- Pilocytic astrocytoma (children, large cystic lesion with central mural nodule)
- Subependymoma (adults, usually in 4th and lateral ventricles), doesn’t enhance
- Central neurocytoma (adults, lateral ventricles attached to septum pellucidum, heterogeneous mass with variable enhancement)
- SEGA tumors (benign, young patients with TS, larger than 1 cm, calcification and marked contrast enhancement)
- Choroid plexus tumors (papilloma, carcinoma)
- Metastases
- Meningioma
List primary brain tumours that diffusion restrict
1) GBM
2) Medulloblastoma
3) Lymphoma
DDx: Infarct, abscess, demyelination
Define pseudoprogression and pseudoresponse
Pseudoprogression - apparent increase in T2 signal in the first 3 months, usu due to radiation or chemo (caution unless clearly outside of XRT field)
Pseudoresponse - apparent decrease in enhancement, typically due to VEGF inhibitors which are anti-angiogenic and alter blood brain barrier; can occur as early as 24-48 hours- persistent findings for 4 weeks are needed to call response
MRS for glioblastoma
Decreased NAA, decreased Cr, decreased myoinosital
Increased choline, increased lactate
Most commonly tumours to bleed
GBM, mets - melanoma, thyroid, choriocarcinoma, RCC
Tumours that are hypointense on T2
- Hypercellular tumours (medullo, lymphoma, germinoma, some GBMs)
- Mucinous mets
Tumours that are hyperintense on T1
Mets - melanoma
Fatty tumours - dermoid/ teratoma
Hemorrhagic mets (RCC, thyroid, melanoma, chorio)
Ependymoma location in adults versus kids
Post fossa of children, spinal cord in adults
“Toothpaste” tumours
Adult spinal tumour can occur anywhere in intramedullary cord - main ddx is astrocytoma (younger patients), difficult to distinguish b/w these on imaging
What is Lhermitte-Duclos imaging appearance and associations
Dysplastic cerebellar gangliocytoma - WHO I
Part hamartoma, part neoplasm
Almost always associated with Cowden syndrome (multiple hamartomas, increased risk Ca)
Tiger-striped lesion cerebellum
ATRT imaging findings
Embryonal tumour - grade 4
Infants/younger patients
Can look like medulloblastoma, heterogeneous, enhancing, +/- edema
Post fossa solid tumour, but also occur supratentorial (ddx: medulloblastoma, embryonal tumours with multi-layerered rosettes i.e. ETMR)
Associated with malignant rhabdoid tumour of kidney
Hemangioblastoma imaging features
WHO Grade 1 - DDX cystic tumour post fossa
Occurs in cerebellum, medulla, or spinal cord
Ass with VHL (in 30% of cases)
Cystic mass, enhancing mural nodule
Prominent flow voids, +/- syrinx
PXA imaging features (pleomorphic xanthoastrocytoma)
WHO Grade II - astrocytoma variant Rare tumour childhood and adolescents Chronic epilepsy Cyst with mural nodule in temporal lobe, dural thickening and enhancement DDx ganglioglioma (more heterogeneous)
Ganglioglioma
Mass in temporal lobe
Similar appearance to PXA
Also in young patient with epilepsy
Won’t see dural thickening like in PXA
Imaging appearance of central neurocytoma
Lobulated mass with cystic foci and calcs attached to septum pellucidum, young adults, good prognosis
Chorioid plexus papilloma/carcinoma
Most common BT in babies**
Hyperintense on T2, enhancing, cauliflower-like
Can see in adults, usu in 4th ventricle
Classic location for SEGA
Enhancing mass, lateral ventricle near Foramen of Munro
Subependymoma demographics and imaging features
Middle age and older adults
Often incidental
4th ventricle most common, or at foramen of munro lateral ventricle
Don’t enhance, so can easily be missed
CNS lymphoma imaging features
Primary: Periventricular, enhancing mass, diffusion restriction, in BG and frontal lobes, can cross CC
Melt away with chemo/rads
Can be heterogenous if immunocompromised, with ring enhancing lesion most commonly seen in BG
DDx: toxoplasmosis (look at perfusion, or do thallium, or PET)
Secondary lymphoma typically involve meninges, may cause leptomeningeal carcinomatosis and dural masses
3 most common primary tumours to met to brain
Lung, breast, melanoma
Multiple meningiomas is associated with _____ or _____
NF2 or prior rads
Most common tumours to met to dura
Breast (#1), lymphoma, small cell lung Ca, melanoma
Key intracranial manifestations of VHL
Hemangioblastomas and endolymphatic sac tumours (along posterior petrous ridge)
DDx CPA angle mass
Schwannoma (#1) Meningioma Arachnoid cyst Epidermoid cyst Aneursym Intra-axial neoplasm
Differences between arachnoid cyst and epidermoid on imaging
Arachnoid - follows CSF on all sequences, FLAIR suppression
Epidermoid - diffusion restriction, does no suppress on FLAIR
