ICL 10.13: CNS Tumors Flashcards
what are the most common tumors in children?
brain tumors
this is because kids don’t get other tumors like lung cancer, and kidney cancer etc.
what are the most common locations of brain tumors in kids vs. adults?
adults = 70% supratentorial
kids = 70% infratentorial
that’s because the top 2-3 tumors in kids happen in the cerebellum
what’s the difference in brain infiltration between primary malignant tumors vs. metastatic malignant tumors?
- primary malignant tumors of astrocyte, oligodendrocytes, or ependymal cells infiltrate the brain because they’re used to that environment
- metastatic malignant tumors in the brain from like lung cancer do not! they don’t like the brain because there’s no collagen, etc. so they cling together as a solid mass. as a consequence, surgeons can usually easily remove brain mets!
what does the clinical course of a brain neoplasm depend on?
the anatomical location!!
there’s different presentations based on if it’s in the brainstem vs. motor cortex vs. speech
do primary brain tumors metastasize outside the CNS?
no!!
what things can cause brain tumors?
- radiation
- immunosuppression
- genetic syndromes
other etiologic factors like cell phones are unproven
which genetic syndromes can cause brain tumors?
- neurofibromatosis
- tuberous sclerosis (astrocytomas)
- Von-Hippel Lindau (hemangioblastomas)
what is the clinical presentation of a brain tumor?
- headache (not specific)
- new onset seizure (most common presenting symptom)
- mental or personality changes (not specific)
- symptoms of increased ICP like nausea, vomiting, drowsiness, blurred or double vision
- possible focal neurological deficits dependent on location
- possible swollen optic nerve = papilledema
what does a cyst indicate?
usually a benign tumor
what does a brain tumor with adjacent edema indicate?
edema suggests rapid growth
what is enhancement? what does it suggest?
contrast dye is injected that won’t cross the BBB
so if you inject enhancement and the lesion lights up, it means it’s damaging the BBB and this indicates malignancy
what are the 4 classifications of tumors?
tumors are classified by what cell they’re made of:
- gliomas
ex. astrocytoma, ependymoma, oligodendroglioma - neuronal
ex. ganglion cell tumors (usually benign) - primitive
ex. medulloblastoma (in the cerebellum of kids) - other
ex. meningioma, hemangioblastoma, lymphoma, metastatic tumors
which brain tumors have a preference for kids?
- poorly differentiated tumors (not just the brain, throughout the body too)
- medulloblastoma*
- pilocytic astrocytoma*
- dysembryoplastic neuroepithelial tumor
- ependymoma*
- ganglion cell tumors
- oligodendroglioma
all 3 of the * are the most common and they’re usually in the cerebellum which is what accounts for most pediatric brain tumors being infratentorial
which brain tumors have a preference for adults?
- astrocytoma
- schwannoma
- central neurocytoma
- meningioma
- glioblastoma (high grade astrocytoma)
which brain tumors have a preference for elderly?
- lymphoma
2. glioblastoma (high grade astrocytoma)
which patient population are lymphomas most common in?
usually seen in immunocompromised patients so this is why brain lymphomas are usually in the elderly but if you’ve got AIDs or organ transplant, you could get a brain lymphoma
what are the most common spinal cord tumors?
OF CORD:
1. astrocytoma
- ependymoma
OF NERVE ROOTS:
1. meningioma
- schwannoma
nerve root tumors are more common
which neural tumors are benign?
- pilocytic astrocytoma
- meningioma
- ganglion cell tumors
- dysembryoplastic NE tumor
- central neurocytoma
- schwannoma
- neurofibroma
schwannomma and neurofibroma are seen in peripheral nerves, not the CNS
which neural tumors are low grade?
- astrocytoma
- oligodendroglioma
- ependymoma
which neural tumors are high grade?
- glioblastoma
- CNS lymphoma
- medulloblastoma
- primitive NE tumor
- malignant peripheral nerve sheath tumor
what are the different grades of astrocytomas?
WHO grade I = benign
malignant:
WHO grade II = astrocytoma
WHO grade III = anaplastic astrocytoma
WHO grade IV = glioblastoma
what are fibrillary/diffuse astrocytomas?
- low grade astrocytoma
- anaplastic astrocytoma
- glioblastoma
so they are malignant WHO grade II-IV astrocytomas
they collectively account for 80% of adult, primary, intraparenchymal brain tumors (so mets, kids and meninges are out)
low grade astrocytomas may progress to higher grade over time
symptoms are critically dependent on anatomic site
what is the average survival length of a fibrillary astrocytoma?
they usually effect 30-60 year olds with higher grades at older ages
low grade astrocytoma = 5 year survival
glioblastoma = 8-10 months
what are the gross changes seen in the brain with a low grade astrocytoma?
- destruction of the hippocampus and temporal horn
it’s destroying normal architecture
- subtle mass effect –> sylvian fissure is pushed up and so are the putamen and globes pallidus
tumor will appear grey even though it’s in the middle of what should be white matter
you can tell it’s low grade because it’s all homogeneous, it all looks like grey matter, there’s no hemorrhage or necrosis, and it got really big without effecting the midline which tells you it was growing pretty slowly
slide 15
what are the microscopic changes in the brain with a low grade astrocytoma?
too many astrocytes and too much pleomorphism (lots of variation in how the cells appear)
what is an anaplastic astrocytoma?
WHO grade III malignant astrocytoma
it’s intermediate grade with intermediate prognosis
Anaplastic astrocytomas generally receive post-operative therapy, unlike low grade astrocytoma
pathology shows greater cellularity and nuclear pleomorphism than a low grade astrocytoma plus mitotic activity
what is a glioblastoma?
WHO grade IV malignant astrocytoma = highest grade
key features:
1. tumor necrosis due to the tumor outgrowing its blood supply
- proliferating balls of small blood vessels responding to VEGF secreted by ischemic tumor cells
what are the 2 ways you can get a glioblastoma?
- dedifferentiation of lower grade astrocytoma into a glioblastoma (more common in younger patients)
- de novo (more common in older patients)
these two tumors are different molecularly
what are the histological features of glioblastoma?
- greater cellularity of astrocytes
- tons of nuclear pleomorphism
- mitotic activity (cells look like they’re trying to divide; reflects growth of tumor)
- tumor necrosis = no blue staining nuclei; the tumor looks white because the tumor cells are dying due to tumor outgrowing its blood supply – you see a ton of cells around this ischemic area and it’s cells trying to run away from the ischemia = pseudopalisading
- microvascular proliferation = proliferating balls of small blood vessels from VEGF secreted by ischemic tumor cells
glioblastoma is a bunch of different colors and it doesn’t all look like a uniform tumor, it looks horrible
slide 19
how do glioblastomas spread?
malignant brain tumors vs. metastatic brain tumors love to infiltrate in the brain, particularly white matter tracts
the corpus collosum is the major white matter tract in the brain and what a glioblastoma does is crawl across to the other hemisphere = “butterfly tumor”(basically diagnostic of a glioblastoma)
which astrocytomas are considered benign?
- pilocytic astrocytoma
- pleomorphic xanthoastrocytoma
- subependymal giant cell astrocytoma of tuberous sclerosis
what is a pilocytic astrocytoma?
WHO grade I astrocytomas that is benign
usually seen in children and usually in the cerebellum in the midline – can also occur in the hypothalamus, optic nerve and brainstem
also usually has a cyst! the cyst is what usually causes the problems too because it outgrows the tumor
so a midline, cerebellar mass with a cyst in a kid, it’s basically 100% a pilocytic astrocytoma
what are the 2 key histological features of a pilocytic astrocytoma?
- alternating biphasic growth pattern of fibrillar and loose areas
- Rosenthal fibers