Term
| why is the distinction between benign and malignant less relevant than w/other neoplasms? |
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Definition
| and increase in intracranial contents = elevated ICP and herniation, therefore all brain tumors will eventually cause death unless removed. |
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Term
| why is complete removal of a brain tumor difficult? |
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Definition
| intrinsic parenchymal tumors do not form capsules |
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Term
| do intrinsic parenchymal tumors metastasize? |
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Definition
| practically never. the may seed along CSF pathways (medulloblastoma in 4th ventricle breaking off and going down cord). |
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Term
| where are most childhood tumors vs adult tumors? |
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Definition
| most childhood tumors are infratentorial, most adult tumors are supratentorial |
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Term
| what are the top three kinds of brain tumor? |
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Definition
| glioblastoma (stage IV astrocytoma), meningoma, and metastatic |
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Term
| what is the general clinical presentation associated w/a brain tumor? |
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Definition
| generalized impairment of cerebral function (most supratentorial), h/a (in waking hours - more ICP at rest), seizures (first occurrence of a focal seizure during adulthood should always alert one to the possibility of a brain tumor), progressive dementia, drowsiness/stupor due to increased ICP, n/v, and dizziness. some specific syndromes: olfactory groove meningoma and optic nerve glioma. |
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Term
| what does the increased intracranial pressure seen in most infratentorial tumors lead to clinically? |
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Definition
| h/a, drowsiness, papilledema, ataxia, and unsteady gait. |
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Term
| what specific syndrome is associated w/acoustic neuromas? |
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Definition
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Term
| what specific syndrome is associated w/pituitary adenomas? |
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Definition
| visual field cut, endocrinopathy |
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Term
| what specific syndrome is associated w/brainstem gliomas? |
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Definition
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Term
| what are the categories of intrinsic brain tumors? |
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Definition
| glial tumors: astrocytoma, glioblastoma multiforme, ependymoma, colloid cyst, and oligodendroglioma. neuronal tumor: medulloblastoma. misc: hemangioblastoma, lymphoma, and metastasis. |
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Term
| what characterizes an astrocytoma? |
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Definition
| histologically, these tend to mimic normal reactions of astrocytes. these are locally invasive w/o clear margins or capsules - and in general, the less malignant the histology, the more infiltrative and less distinct the astrocytoma is from surrounding brain (making removal difficult). there is preference for the cerebrum, cerebellum, optic nerve and hypothalamus by astrocytomas. |
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Term
| what characterizes a grade II astrocytoma on MRI? |
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Definition
| there is less edema/mass effect relative to that seen in other tumors |
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Term
| what is the 5 yr survival for the different types of astrocytoma? |
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Definition
| grade I: 76%, grade II: 58%, grade III: 6% |
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Term
| what is a cerebellar astrocytoma? |
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Definition
| these are only seen in children and often occur as a cyst w/a mural nodule (extremely well encapsulated). if complete removal: 90% survival (histologically benign and easily accessible via sx). |
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Term
| what characterizes a brainstem glioma (type of astrocytoma)? |
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Definition
| these are slow growing, infiltrative cystic tumors which grossly appear as enlargements of the brainstem. peak incidence = 7 y/o and they present as a CN palsy followed by long tract signs. since they are slow growing, they are resistant to chemotx/XRT and since they are in a vital location, removal is impossible. |
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Term
| what characterizes the glioblastoma multiforme (astrocytoma grade IV) histologically? |
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Definition
| pleomorphism, capillary proliferation, central necrosis, and rapid growth (b/c rapidly growing the tumor outstrips blood supply and there’s an area of central necrosis). usually these arise in the cerebral hemispheres, but if they arise in the corpus callosum = butterfly glioma. |
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Term
| what is the prognosis for glioblastoma multiforme (astrocytoma grade IV)? |
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Definition
| mean survival after sx = 8 mos. chemotx and XRT are minimally effective. |
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Term
| why might glioblastoma multiforme (astrocytoma grade IV) look somewhat cystic on MRI? |
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Definition
| this is due to the central necrosis |
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Term
| what characterizes ependymomas? |
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Definition
| these arise from the ependymal cells in the lateral, 3rd, (adulthood) or 4th ventricle (childhood). 50% 5 yr survival if the pt survives sx (histologically benign but surgery removal is difficult b/c of depth). a shunt may be necessary to get rid of excess fluid. |
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Term
| what characterizes colloid cysts? |
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Definition
| theses are also derived from ependymal cells and are located on the anterior position of the *3rd ventricle. these will often cause a ball-valve obstruction: recumbent->foramen open->normal ICP, standing->foramen blocked-> increased ICP. tx: shunt +/- removal. |
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Term
| what characterizes medulloblastomas? |
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Definition
| these are the only neuronal tumors and arise from the embryonic remnant of the external granular cell layer of the cerebellum - almost exclusively in children on the roof of the 4th ventricle. these may seed widely throughout the CSF space but are highly radiosensitive. *most common brain tumor of children. medulloblastomas are also called PNETs – pediatric neuronal ectodermal tumors. |
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Term
| what characterizes lymphomas in the brain? |
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Definition
| aka reticulum cell sarcomas, these are of unknown origin in the brain (may be first manifestation of systemic lymphoma). there is a predilection for immunocompromised pts (AIDS) and they are very steroid sensitive. these are typically multicentric and have predilection for periventricular regions. most common ddx: toxoplasmosis (typical w/u would include toxo Ab) |
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Term
| what are the most common brain tumors? what characterizes their incidence? |
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Definition
| metastases - often multiple lesions and well encapsulated (distinguishes them from malignant primary brain tumors). 20% of all pts dying of CA have evidence of brain metastasis at autopsy. 74% of pts w/melanoma have CNS mets. lung CA also commonly metastasizes to the CNS. |
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Term
| what characterizes brain metastasis evaluation? |
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Definition
| if CT/MRI shows single lesion, it may be primary or metastatic. if multiple lesions, it is almost always metastatic. if the pt has a known primary tumor, no additional w/u is usually necessary - but if none is known: CXR/CT scan of chest and CT scan of abdomen/pelvis. if no primary tumor identified -> bx or removal. |
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Term
| what are the extrinsic brain tumors? |
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Definition
| meningoma, craniopharyngioma, pituitary adenoma, pineal tumors, and acoustic neuroma |
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Term
| what characterizes meningiomas? |
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Definition
| these arise slowly (less mass effect) from benign arachnoid cells and commonly indent the brain and calcify in these common sites: sylvian region, parasagittal region, sphenoid bone and CP angle. presentation depends on location and sx is curative if accessible. (neurologic syndrome from parasagittal meningiomas is called cerebral paraplegia - mimics spinal cord syndrome) |
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Term
| what is a craniopharyngioma? |
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Definition
| a congenital tumor arising from rathke's pouch which is often cystic and calcified - almost always in the suprasellar region. they are histologically benign, but "malignant" b/c of location. 5 yr surival = 75%. can cause obstructive hydrocephalus. |
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Term
| what characterizes pituitary adenomas? |
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Definition
| histologically benign tumors which can grow out of the sella and compress the optic chiasm = visual field deficit (only really gets to this point if tumor is endocrinologically silent). pituitary adenomas can also cause hormonal disturbance: hyperfunction due to endocrine secretion or hypofunction due to compression of the pituitary. tx: trans-sphenoidal sx for macroadenoma, bromocriptine for microadenoma. |
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Term
| what characterizes the pineal tumors? |
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Definition
| these may be seminoma, germinoma or teratoma and present *w/parinaud's syndrome: limitation of upgaze and dilated pupils (superior colliculus/edingerg westphal nucleus). |
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Term
| what characterizes an acoustic (vestibular) neuroma? |
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Definition
| these arise in the internal auditory canal on the vestibular portion of CN8 (cerebellar-pontine angle) - from schwann cells. pts present w/*unilateral* hearing loss, tinnitus, vertigo, unsteadiness, facial hypesthesia (facial weakness due to trigeminal nerve) and ataxia. tx: microsx |
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Term
| what is the goal of tx for primary CNS neoplasm sx? |
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Definition
| remove as much tumor as possible w/o compromising vital CNS tissue (optic chiasm, brainstem, dominant hemisphere). |
|
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Term
| what is the goal of tx for primary CNS neoplasm radiotherapy? |
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Definition
| gliomas, craniopharyngiomas, lymphomas and medulloblastomas |
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|
Term
| what is the goal of tx for primary CNS neoplasm chemotherapy? |
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Definition
| minimally effective except in lymphoma and medulloblastoma. temazolamide: astrocytoma III and glioblastoma. |
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Term
| what is the goal of tx for primary CNS neoplasm steroid treatment? |
|
Definition
| reduce vasogenic edema (for every gram of malignant tumor, there are at least 2 grams of brain edema) |
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|
Term
| what is tx for metastatic brain tumors? |
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Definition
| sx if no other evidence of systemic disease/isolated or major compromising tumor. whole brain irradiation. corticosteroids. chemo = ineffective due to BBB. |
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