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180 Cards in this Set

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BRAIN TUMORS - NELSON - WEDNESDAY JAN 24
what age group do CNS tumors account for a high percentage of (and what percentage)?
children - account for 21% of childhood neoplasms
why can a tumor cause more damage to the brain than other organs?
because the CSF and blood are not compressible, and the brain is enclosed by a rigid skull, a space-occupying brain lesion can damage the tissue
where do CNS tumors most often metastasize?
nowhere - they do not metastasize elsewhere in the body
what is the prognosis for tumors made of primitive neuroectodermal cells, and why?
very bad, because they diide a lot
what other cells can be derived from primitive neuroectodermal cells that can cause tumors (3)?
1) neuron; 2) oligodendrocyte; 3) astrocyte
how much do each of these cells divide, and what is the prognosis for a tumor composed of each type?
1) neuron - does not divide, good prognosis; 2) oligodendrocyte - divides some, bad prognosis; 3) astrocytes - divide more, very bad prognosis
what are the general signs and symptoms of a brain tumor (6)?
1) headache; 2) nausea/vomiting; 3) behavioral/personality change; 4) speech change; 5) slowing of psychomotor function; 6) visual change
in what % of patients are seizures the presenting symptoms?
20%
what symptoms are associated with the temporal lobe (3)?
1) seizures; 2) hallucinations; 3) receptive aphasia
what symptoms are associated with the occipital lobe?
visual
what symptoms are associated with cerebellum?
ataxia
a tumor in which location will cause autonomic, hormonal, and emotional disruptions?
hypothalamus
what does tumor type describe about a tumor?
the cell of origin
what two main types were mentioned?
1) glial; 2) neuronal
what subtypes of glial tumros (gliomas) were mentioned (2)?
1) astroglial (astrocytoma); 2) oligodendroglial (oligodendroglioma)
what are the four specific brain tumors that we should be aware of (4)?
1) medulloblastoma; 2) glioblastoma multiforme; 3) schwannoma/neurofibroma; 4) meningioma
MEDULLOBLASTOMA
where does medulloblastoma arise, and is it malignant?
arises in the cerebellum, and it is malignant
what fraction of posterior fossa lesions in children does this account for?
one third
where is the posterior fossa (boundaries, and what areas are included)?
beneath the tentorium cerebelli and includes all cerebellar and brainstem lesions
where in this area precisely does the tumor generally arise in children, and what % arise there?
75% arise in the vermis (midline) in children
in young adults, where does a medulloblastoma usually arise?
in lateral hemisphere of cerebellum
what is the tumor like in density, and what type of cells is it composed of (shape and staining properties)?
densely cellular, generally homogeneous, and composed of small round or oval densely basophilic cells
how are these cells arranged (3 possibilities)?
1) rosettes; 2) parallel rows; 3) forming sheets
are there few or many mitotic figures?
mitotic figures are numerous
what do medulloblastomas have a propensity to invade (2), and what type of response do they produce when they invade this?
marked propensity to invade the leptomeninges (producing a desmoplastic response)
what may these tumors then seed into?
CSF pathways of subarachnoid space and ventricles
what fraction of children will have seeded the CSF at the time of their diagnosis?
over 1/3
what is the five year survival % for medulloblastomas?
50-70%
what type of therapy is used that produces morbidity?
therapy includes total irradiation of the CNS and can have pronounced morbidity, including damage to normal neuronal structures
what age of presentation has a poor survival risk?
<3yr
what genetic changes lead to a poor survival risk for medulloblastoma (2)?
1) amplification of MYC gene; 2) LOH (loss of heterozygosity) of 17p (in association with MYC)
what variant of medulloblastoma is biologically aggressive and has a significantly shorter survival?
the large cell variant
what are prognostic factors for favorable outcome (tumor immuno expression of 3 things)?
1) retinal-S antigen; 2) rhodopsin; 3) TrkC receptor
GLIOBLASTOMA MULTIFORME (AND OTHER GLIOMAS)
what % of primary glial tumors are glioblastoma multiforme (GBM)?
65%
at what age is the peak incidence?
6th decade - usually adults
are glioblastoma multiforme generally infratentorial or supratentorial?
supratentorial
what are they like as far as growth and mitosis?
high mitotic rate, rapid growth
what else are they characterized by (4)?
1) necrosis; 2) vascular endothelial proliferation; 3) dense hypercellularity; 4) high degree of anaplasia
what may tumors show around zones of necrosis?
pseudopalisading
what other type of foci are common in glioblastoma multiforme?
hemorrhagic
is the tumor homogeneous?
no, it may often be a regionally variable mixed tumor
what types of zones may it display (4)?
1) primative neuroectodermal; 2) differentiated astrocytoma; 3) oligodendroglimoa; 4) ependymoma
what locations may the more differentiated parts (astrocytoma, oligodendroglioma, or ependymoma) dominate?
periphery of the lesion
what error can this lead to?
if a superficial biopsy is obtained, an erroneously low grade may be ascribed to the tumor
compared to other gliomas, how invasive are GBM's, and how are they graded?
the most invasive and aggressive of the gliomas, and are WHO grade IV tumors
what types of invasion was it said they are capable of (5)?
1) infiltrate subpial zones; 2) extend along perivascular (Virchow-Robin) spaces; 3) invade leptomeninges/pachymeninges; 4) seed the CSF; 5) cross corpus callosum
how often do these tumors recur?
always, even after apparent total surgical removal
what is the approximate length of survival without treatment?
three months
what about with surgical treatment?
six months
what about with surgery and radiation?
10-12 months
what glioma is like a GBM but lower grade?
diffuse astrocytoma
DIFFUSE ASTROCYTOMA
what % of gliomas are they?
20%
what are they most often composed of, and where?
most often white matter tumors of the cerebral hemispheres
what is the most characteristic feature of diffuse astrocytomas?
their tendency to diffusely infiltrate without clear margins
how often are they resectable?
very rarely
how does their grade change over time?
it progresses from low to high grade (becomes more anaplastic)
what does survival generally correllate with?
histologic grade of tumor
in general, what is the grade of a diffuse astrocytoma based on (3)?
1) degree of hypercellularity/atypia; 2) endothelial changes; 3) necrosis
what is an important subgroup of diffuse astrocytomas?
brainstem gliomas
who do they normally occur in (age)?
children in second decade
where do they appear in the brainstem, and do they infiltrate?
typically occur in the pons, and infiltrate widely
which of the histologic grades can they fall in?
full range, including glioblastoma
can they be surgically removed?
no, because of location
what do patients generally present with (list)?
cranial nerve palsies, long tract signs, gait abnormalities, emesis, and cerebellar signs (all due to tumor location in CNS axis)
PILOCYTIC ASTROCYTOMA
how do pilocytic astrocytomas compare do their diffuse relatives as far as grade, invasiveness, and histological pattern?
they are generally circumscribed and almost always low grade, with a distinctive histologic pattern
what age group do they tend to occur in?
children and young adults
where does the tumor generally arise?
midline (but occur throughout the neuroaxis)
what structures does the tumor generally involve (3)?
1) cerebellum; 2) hypothalamus; 3) optic chiasm/nerves
what is the histologic pattern of most like?
biphasic, with loose and densely cellular areas randomly intermingled
what else are frequently identified in the neoplasm?
microcystic areas containing regionally variable amounts of mucinous proteinaceous material
what shape are the astrocytes, and what structures do they form?
astrocytes are elongated and bipolar, and tend to form Rosenthal fibers
what do Rosenthal fibers look like (what shape, and how do they stain)?
opaque, homogeneous eosinophilic, carrot-shaped or beaded masses in the astrocytes
what do Rosenthal fibers consist of unltrastructurally?
greatly thickened, electron dense glial filaments
where else may Rosenthal fibers occur (besides this type of tumor)?
in association with areas of long standing reactive gliosis - around the periphery of craniopharyngiomas or syringomyelic cavities - they are not specific to pilocytic astrocytomas
what are optic nerve gliomas often associated with?
neurofibromatosis type I (Von Recklinghausen's disease)
OLIGODENDROGLIOMA
what % of primary CNS neoplasms are oligodendrogliomas?
5%
in what age group are they most common?
can occur in any, but are typically tumors of adults
at what location in the brain do they occur?
any
what areas is most common?
cerebral white matter
what common feature of oligodendrogliomas may be seen on skull films or CT?
focal calcification
what characteristic appearance do "pure" well differentiated oligodendrogliomas have?
fried egg appearance (nuclei of cells are regularly round, and cytoplasm is watery and clear)
what is the typical grade of oligodendrogliomas?
grade II
what is the blood supply of oligodendrogliomas like?
highly vascularized
what do features such as necrosis, endothelial proliferation, cell density, and pleomorphism indicate about oligodendrogliomas?
unlike other tumors, these features do not correllate well with aggressive biologic behavior
what is the speed of growth of most oligodendrogliomas?
slow, although some may be highly aggressive
what is the median postoperative survival?
3-5 years (for all grades)
what is the best predictor of biologic behavior and response to therapy in oligodendrogliomas (2)?
1) loss of heterozygosity in short arm of chromosome 1 (LOH 1p); 2) LOH in long arm of chromosome 19 (LOH 19q)
what is the outlook for patients harboring tumors having combined loss of 1p and 19q?
favorable response to chemotherapy and 95% five year survival
what genetic change will cause tumors to be biologically aggressive, with a survival of <2yrs?
CDKN2A deletion
what do oligodendrogliomas often occur as mixed tumors with?
astrocytic tumors
EPENDYMOMA
what % of primary intracranial neoplasms are ependymomas?
5%
where may they occur?
in any area of the ventricular system
what is the most common intracranial site of occurrence for ependymomas, and what % occur there?
fourth ventricle - 70% of ependymomas
what age groups do ependymomas situated in the cerebral hemispheres occur?
evenly distributed in all age groups
at what age are infratentorial ependymomas most common?
first decade of life
in general, at what ages are ependymomas most common?
childhood and adolescence
what are ependymomas said to be the most common example of?
spinal intramedullary gliomas (they account for 63% of all spinal intramedullary gliomas)
what disorder are spinal ependymomas a major manifestation of?
neurofibromatosis type 2
how well differentiated are ependymomas, generally?
well differentiated (although malignant ependymomas do occur)
how often do ependymomas infiltrate the brain?
not often - they are usually well demarcated and do not infiltrate
what structures are prominent in ependymomas?
blood vessels
what type of density can they have?
can be solid, papillary, or both
what are the two inconstant features that are highly diagnostic for ependymomas (2)?
1) ependymal rosettes; 2) perivascular pseudorosettes
what are ependymal rosettes?
groupings of ependymal cells around true or potential circular cavities
what is survival rate a function of (3)?
1) tumor location; 2) extent of resection; 3) CSF dissemination (presence or absence)
what is the best, next best, and worst location to have an ependymoma?
spinal cord, cerebrum, posterior fossa
SCHWANNOMA
what are schwannomas and neurofibromas tumors of?
nerve roots and peripheral nerves
what is a schwannoma located in association with CN VIII?
acoustic neuroma
what is a schwannoma composed of (cells) and how fast does it grow?
composed of schwann cells and generally benign and slow growing
what type of nerves do they generally arise on?
sensory nerves (although they can arise on motor, mixed, or autonomic nerves)
what are the three types of schwannomas (by location)?
1) intracranial; 2) intraspinal; 3) peripheral
what is the most common location for intracranial schwannomas?
along 8th nerve, in cerebello-pontine angle
at what specific point does this tumor arise (acoustic neuroma)?
at the transition between schwann cells and oligodendroglial cells at the internal auditory meatus
what is the second most common intracranial site for schwannomas?
along 5th cranial nerve
what sex is most likely to get an intracranial schwannoma?
females
what is the presence of bilateral acoustic neuromas indicative of?
indicative of NF-2
what % of intraspinal tumors are schwannomas?
30%
at what levels of the spine do they occur, and with what frequency?
at all levels with same frequency
what is more likely to happen to intraspinal schwannomas than intracranial schwannomas?
intraspinal schwannomas are more likely to become cystic
how common are peripheral schwannomas?
uncommon, and usually solitary
if there are multiple peripheral schwannomas, what may they be a part of?
NF1 / von Recklinghausen's disease
how often do they become malignant?
rarely, except for in association with NF1
NEUROFIBROMA
where may neurofibromas arise from (2)?
1) small peripheral nerves; 2) large nerve trunks
what type of masses do those arising from peripheral nerves form (are they localized and are they encapsulated, and what is their shape)?
localized but unencapsulated soft pedunculated masses
what are the schwann cells intermixed with in these neurofibromas?
a network of collagen, reticulin fibers, and fibroblasts
in contrast to schwannomas, what may neurofibromas represent?
a kind of hyperplasia of the schwannian and fibroblastic supporting elements of the nerve
what does this hyperplasia cause?
dissociation fo the individual nerve fibers within the tumor
are neurofibromas more commonly solitary or multiple?
more commonly multiple
what are multiple neurofibromas associated with?
NF-1
what special type oof neurofibroma is pathognomic for von Recklinghausen's disease?
plexiform neurofibroma
MENINGIOMA
what % of intracranial neoplasms, and what % of intraspinal tumors, are meningiomas?
15% of primary intracranial, 25% of intraspinal
when in life are they most common (age)?
after third decade - maximal incidence around age 45 - very rare in children
what sex are they more common in?
females (3:2)
what subset of meningiomas are strikingly more common in females (10:1)?
intraspinal meningiomas
what is the tumor like in cell arrangement, cell borders, and nuclei?
sheets of cells with poorly defined borders and bland medium sized round to oval nuclei
what is there a propensity for formation of (2)?
1) cellular whorls; 2) variable numbers of psammoma bodies
what are psammoma bodies?
microscopic, round, calcified structures
how vascularized are meningiomas?
may be quite vascular
what are tumors usually attached to?
the dura
how fast do they grow, and are they benign or malignant?
generally slow growing and essentially benign
what are the three types of meningiomas based on location, and what is the frequency of each (%)?
1) convexity meningioma (50%); 2) basal meningioma (40%); 3) posterior fossa meningioma/foramen magnum meningioma (10%)
where are convexity meningiomas located (3 possibilities)?
1) parasaggital; 2) falcine; 3) lateral convexity
where can basal meningiomas be located (4)?
1) olfactory groove; 2) sphenoid wing; 3) pterion; suprasellar
in what pattern do meningiomas grow, and what problem can they cause?
they grow by expansion and will compress the adjacent brain
what do these tumors infiltrate (2)?
they do not infiltrate the brain, but commonly infiltrate the dura and adjacent bone
what can they cause by infiltrating dura and bone?
hyperostotic (thickening) response in bone
what is seen in bone when this response occurs?
radiating spicules
what do these tumors have a tendency to do after excision?
recur (10-15%)
how often are menigiomas malignant?
rarely
what features are associated with malignancy (3)?
1) invasion of brain parenchyma; 2) tumor necrosis; 3) metastasis
what types of meningioma is histologic subtyping important in (4), and why?
clear cell, rhabdoid, chordoid, and papillary types - because these have a tendency for aggressive behavior and recurrence