31b - Pediatric Brain Tumors Flashcards
Where is the most common site for PED tumors: supratentoria, infretentorial, or midline?
infratentorial most common in PEDs.
What are supratentorial peds tumors?
suprasellar (chiasmal glioma, craniopharyngioma)
hemispheric (astrocytoma)
pineal
What are infratentorial tumors in peds?
Most common are cerebellum and 4th ventricle
>posterior fossa (medulloblast, astrocy, ependy, and glioma)
What is most common pediatric solid tumor?
brain tumor
What is survival rate for brain tumors in 1st decade?
65%
What is most common Peds tumor?
astrocytoma>PNET>gliomas>ependymomas
What are Cowden (xPTEN) syndromes risks for?
high mTOR. dysplastic gangliocytoma in cerebellum
What are nevoid basal cell carcinoma/gorlin syndrome risks for?
medulloblastoma (ch. 9, PTCH mutation)
What is an APC gene mutation a risk for?
turcot syndrome, medulloblastoma and GBM
What is likely location of a tumor causing localized seizures and hemiparesis?
supratentorial
What symptoms would you expect for a midline tumor?
endocrinopathies, hydrocephalus (early AM headache with n/v, bulging fontanelle, sundowning eyes, CN6 palsy)
What are signs of a infratentorial tumor?
high ICP due to compression of 4th ventrical.
papilledema w/blurring of optic disk
What are signs of brainstem tumor?
diplopia, dysarthria, dysphagia. crossed weakness (lesion rostral to pyramidal decussation) = ipsilateral CN function and contralateral UMN findings.
What is JPA? Where is it commonly olcated?
juvenile pilocystic astrocytoma (grade 1).
usually supra or infratentorial, most on posterior fossa.
What can JPA progress to?
GBM
What is pathogenesis of JPA?
mutation of BRAF (fusion or v600e) and NF1 cause oncogenic process of MAPK path.
mtuations activate RAF and MAPK pathways that incrase nuclear transcription.
Where are BRAF fusion mutation tumors common?
BRAF v600e?
fusion = cerebellum v600e = extracerebellum
Whhere are NF1 mutation types of JPA common?
optic pathways
What is gross appearance of JPA?
cYSTIC.
what is microscopic pathology of JPA?
pilocytic, hair like projections off neoplastic cells ROSENTHAL FIBERS that are GFAP+.
Hyalinization of blood vessels
What is prognosis for JPA?
good, it is low grade
What is medulloblastoma?
a highly malignant primitive tumor of the CEREBELLUM.
What is PNET?
highly malignant primitive tumor of the CEREBRUM
What are histochemical markers for medulloblastoma and PNET?
TrkC, Erb, C-myc, neurotrophinin
What is pathogenesis of medulloblastoma?
SHH and Wnt pathways.
inactive SHH has high Ptch inhibition of smooth cilium transfer so high degradation of smoothened and SufU-Gli2/3
Active SHH has low PTCH inhibition so active smoothened to cilium transfer so decreased SuFu mediated gli2 degradation adn increased gli2 transcription
Inactive WNT has inactive frizzed receptors and increased B-catenin phosphorylation/degradation
Active Wnt has active Frizzled receptors and high B-catenin to nucleus transcription
What is best prognosis for medulloblastoma?
wnt > smoothened/PTCH > c-myc (bad)
Why is medulloblatoma difficult for resection?
it spready via CSF to other structures
What type of tumor has round, blue carrot shaped cells with Homer wright rossette?
medulloblastoma
Is medulloblastoma sensitive to radiotherapy?
you betcha
What is a brainstem glioma?
subgroup of astrocytoma.
diffuse intrinsic pontine glioma.
Terrible prognosis.
What is gross pathology/MRI finding for brainstem glioma?
tumor that engulfs tha basilar artery
What is clinical presentation for brainstem glioma?
classic triad: CST long tract sings of weak/hemiparesis, ataxia, and CN6,7,8 signs.
What is ependymoma?
tumor of ependymal lined ventricles
What is the PNET variant of ependymoma?
ependymoblastoma
Tumor is found growing into ventricular system, histo shows perivascualr psuedorossettes. what do you suspect
ependymoma
What is micropath for ependymoma?
perivascular pseudorossettes
Which peds tumor can you NOT perform surgery on?
brain stem glioma
How long should you try to hold off on radiation therapy in kids?
until at least 3, best if after 7 so they can develop. Will have defecits if treated early.
