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44 Cards in this Set

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Creutzfeldt-Jacob Disease
(CJD)
a. Caused by a prion protein (PrP)
i. PrP is a 30-kD protein normally present in neurons
ii. Encoded by a single-exon gene on chromosome 20
iii. Its normal conformation is an (X-helix:PrPC
iv. In disease states, Prpe changes to a p-pleated sheet conformation: Prpse
v. Low spontaneous change results in sporadic cases of CJD
vi. Mutations of PrP result in hereditary cases of CJD
vii. Prpse facilitates conformational change of other Prpe molecules into Prpse
viii. Prpse is responsible for cerebral pathologic changes
b. Results in spongiform change
i. Fine vacuolization of the neuropil in the gray matter (especially cortex)
ii. Due to large membrane-bound vacuoles within neuronal processes
iii. Associated with neuronal loss and astrogliosis
iv. Kuru plaquesare deposits of amyloid of altered PrP protein
c. What are the clinical manifestations of spongiform encephalopathies?
i. CJD: 85% cases are sporadic; 15% are familial
ii. Middle-aged to elderly patients
iii. Rapidly progressive dementia
iv. Memory loss with startle myoclonus or other involuntary movements
v. Typical EEG changes
vi. Death within 6-12 months
Cerebrovascular Disease
Cerebrovascular Disease
1. Etiology
a. Third most frequent cause of death in industrialized countries
b. Leading cause of serious disability in the United States
c. Risk factors similar to coronary artery disease
2. Clinicopathological forms
a. Global cerebral ischemia
i. Fall in blood flow to the brain (shock, cardiac arrest, and hypotensive episodes)
ii. Damage to regions of selective vulnerability: Purkinje neurons, hippocampus
CAl, and pyramidal neurons of cortex
iii. Infarcts in watershed areas
IV. Cortical laminar necrosis
. Diffuse ischemic necrosis of neocortex
. May lead to brain death
b. Transient ischemic attack (TIA): reversible, symptoms last less than 24 h; due to
small platelet thrombi or atheroemboli
c. Infarction: 85% of all stroke cases
i. Thrombosis of cerebral artery (atherosclerosis-related)
ii. Cardiogenic embolism
iii. Small-vesseldisease: arteriolosclerosis, amyloid angiopathy, etc.
d. Hemorrhage: 15% of all stroke cases
i. Intracerebral
ii. Subarachnoid
Infarction
Infarction
a. Thrombotic occlusion
i. Due to atherosclerosis
ii. Leads to anemic (white) infarct
b. Embolic occlusion
1. Often due to throniboemboli from cardiac chambers
ii. Less frequently due to atheroemboli
iii. Leads to hemorrhagic infarct
c. Small-vessel disease
i. Related to hypertension, resulting in hyaline arteriolosclerosis
ii. Leads to lacunar infarcts or lacunae
d. Pathology (ie, morphological features of brain infarcts)
Common neurovascularsyndromes
i. Anterior cerebral artery (ACA)
. Weakness and sensory loss in contralateral leg
. Transient expressiveaphasia . Abulia (loss of will or motivation)
n. Middle cerebral artery (MCA)
. Contralateral hemiplegia (face and arm) and gaze palsy
. Contralateral sensory loss
. Aphasia if dominant hemisphere affected
ill. Posterior cerebral artery (PCA)
. Contralateral hemianopia or total cortical blindness if bilateral
. Alexiawithout agraphia . Thalamic syndrome
iv. Dementia: due to recurrent infarcts or small vesseldisease
Hemorrhage
a. Causes 15%of strokes
b. Intracerebral (intraparenchymal) hemorrhage
i. Hypertension: most frequent predisposing condition; involves basal ganglia,
cerebellum, pons, and centrum semiovale
ii. Other causes: vascular malformations, especially arteriovenousmalformations
(AVMs), cerebral amyloid angiopathy, neoplasms, vasculitides, abnormal
hemostasis, hematological malignancies, and infections
ill. Symptoms: severe headache, frequent nausea/vomiting, steady progression of
symptoms over 15-20 minutes, and coma
Hemorrhage
c. Epidural hemorrhage
i. Virtually alwaystraumatic
ii. Usually associated with skull fracture
iii. Tear of dural arteries, most frequently middle meningealartery
iv. Leads to cerebral herniation (usually subfalcine) if not promptly evacuated
v. Lucid interval before loss of consciousness ("talk and die syndrome")
d. Subdural hemorrhage
i. Usually traumatic
ii. Caused by rupture of bridgingveins (from cerebral convexitiesto sagittal sinus)
iii. Predisposing conditions: brain atrophy and abnormal hemostasis
iv. Headache, drowsiness, focal neurological deficits,sometimes dementia
v. Recurs frequently
e. Subarachnoid hemorrhage
i. Most frequent cause: ruptured berry aneurysms
ii. Lessfrequent causes:extension of an intracerebral or subdural hematoma, vascular
malformations, trauma, abnormal hemostasis, and tumors
iii. Sudden ("thunderclap") headache, nuchal rigidity, neurological deficits on one
side, and stupor
Berry aneurysms
a. Thin-walled saccular outpouchings, consisting of intima and adventitia only
b. Most frequent cause of subarachnoid hemorrhage
c. Most frequent sites: anterior circle of Willis at branching points
d. Pathogenesis: congenital focal weakness of artery; not identifiable at birth
e. Associated disorders: Marfan syndrome, Ehlers-Danlos type 4, and adult polycystic
kidney disease
f. Hypertension and cigarette smoking predispose to formation
g. Rupture is precipitated by sudden increase in blood pressure
h. Prognosis after rupture: 1/3 die, 1/3 recover,and 1/3 rebleed
Multiple sclerosis
a. Definition: chronic relapsing-remitting disorder of probable autoimmune origin
characterized by recurrent episodes of demyelination in the brain (including optic
nerves) and spinal cord, which results in progressive neurological deficits
b. Epidemiology
i. Overall prevalence: 1/1,000
ii. Prevalence higher in northern countries
iii. Persons who emigrate after age 15 from areas of high prevalence to areas oflow
prevalence maintain original risk
iv. Women have double the risk of men
v. Clinical onset in the third or fourth decade
Multiple sclerosis Etiopathogenesis
i. Multifactorial
ii. Genetic factors
. Familial propensity
. Concordance rate in twins:25% in monozygotic,2% in dizygotic
. Strong association with HLA-DR2
iii. Immune factors
. Oligoclonal CD4 lymphocytic infiltration
. Experimental allergic encephalitis (EAE) obtained by injection of myelin
basic protein (MBP)
. THI cytokines (IF-y and TNF) facilitate; TH2 cytokines (IL-4 and IL-lO)
retard EAE
iv. Infectious agents (suspected, not proven): mumps, rubella, herpes simplex,
measles, and JC virus
Multiple sclerosis Pathology
i. Acute lesions: well circumscribed plaques, with loss of myelin
. Gross: well circumscribed, frequently periventricular, with same color as
gray matter
. Histology: chronic inflammation with phagocytosis of myelin by
macrophages; axons are initially preserved
ii. Chronic lesions: no inflammation, with axons showing remyelination
iii. Remyelination is defective because myelin sheaths are thinner with shorter
internodes
e. Pathophysiology
i. Acute attack: nerve conduction is entirely blocked, acute neurological deficits
ii. Chronic plaque: slower nerve conduction, allowing for partial recovery
iii. Recurrent attacks: progressive neurological deterioration
f. Clinical course
i. 85% cases: relapsing-remitting course
ii. Minority: primary progressive (slow deterioration) or progressive-relapsing
(slow progression punctuated by acute exacerbations) course
iii. Recoveryfrom each episode of demyelination occurs in weeks or months
Multiple sclerosis Symptomatology & Treatment
i. Blurred vision or loss of vision in one eye (optic nerve involvement)
ii. Diplopia and vertigo (brainstem involvement)
iii. Loss of sensation or weakness in one leg (spinal cord involvement)
iv. Hemiparesis or loss of sensation in half of the body (cerebral white matter
involvement)
v. Many other symptoms, sometimes of neuropsychiatric nature
h. Treatment
i. Acute attack: high-dose steroids facilitate recovery
ii. Chronic treatment slows progression of disease
iii. Interferon-beta
iv. Copolymer 1 (Copaxone)
Central pontine myelinolysis (CPM)
a. Focal demyelination of central area of basispontis
b. Patients at risk: severelymalnourished, alcoholics,with liver disease
c. Probably derives from rapid correction of hyponatremia
d. Veryoften fatal
Parkinson disease and syndrome
a. Definition
i. Loss of dopaminergic neurons in the substantia nigra
ii. Tremor, rigidity, and akinesia
iii. Parkinson disease (PD) is the idiopathic form
iv. Parkinson syndrome (PS) is secondary to known injuries to the substantia
nigra (SN) (e.g., infections, vascular conditions, toxic insults)
b. Epidemiology
i. Common disease:2% of the population
ii. PD arises in the fifth to eighth decade of life
iii. No genetic-familial, sex, or race predisposition
Parkinson disease Etiopathogenesis & Pathology
i. Loss of dopaminergic neurons is unexplained in PD
ii. Theories emphasize oxidative stress
iii. Accidental exposure to 1-methyl-4-phenyl-l,2,3,6-tetrahydropyridine
(MPTP) causes death of dopaminergic neurons in SN
iv. MPTP is a by-product of illicit synthesis of meperidine analogue
d. Pathology
i. Gross: pallor of SN
ii. Histology: loss of pigmented (dopaminergic) neurons in SN
. Lewy bodies: intracytoplasmic round eosinophilic inclusions that contain
alpha-synuclein; EM shows filaments most likely of cytoskeletal origin
iii. Secondary degeneration of dopaminergic axons in the striatum
e. Pathophysiology
i. Loss of extrapyramidal nigra-striatalpathway
ii. Inhibition of movement of proximal muscles and disruption of fine regulation
of distal muscles
iii. The pathophysiologic basis of PD-associated dementia is not clear
Parkinson disease Treatment
Clinical manifestations
i. Slowing of all voluntary movements
ii. Tremor at rest that disappears during movement
iii. Expressionless face
iv. Rigidity of limbs and trunk and inability to initiate voluntary movement
v. Increased incidence (20-40% of patients) of dementia and depression
g. Treatment and prognosis: Levodopa treatment of choice usually combined with
other drugs
Concussion
i. Change in the momentum of the head (impact against a rigid surface)
ii. Loss of consciousness and reflexes,temporary respiratory arrest, and amnesia
for the event
iii. Pathogenesis uncertain
iv. Parenchymal injuries may or may not be evident at autopsy
Contusions
i. Impact of parts of brain against inner calvarial surfaces
ii. Bruising to the brain resulting from tissue and vesseldisruption
iii. Sites of injury: crests of orbital gyri in frontal and temporal poles
iv. Coup (site of injury) and contrecoup(site diametrically opposite)
v. Coup and contrecoup develop when the head is mobile at the time of impact
vi. Acute: hemorrhage of brain tissue in a wedge-shaped area
vii. Subacute:necrosis and liquefaction of brain
viii. Remote: depressed area of cortex with yellow discoloration ("plaquejaune")
Diffuse axonal injury
i. Injury to the white matter due to acceleration/deceleration
ii. Damage to axons at nodes of Ranvier with impairment ofaxoplasmic flow
iii. It is diffuse,but predilection for
. Corpus callosum, periventricular white matter, and hippocampus . Cerebral and cerebellar peduncles
iv. Coma after trauma without evidence of direct parenchymal injuries
v. Poor prognosis, related to duration of coma
vi. Histopathology:axonal swellings appreciable in the white matter
Spinal cord injury
a. Injuries are usually traumatic, due to vertebral displacement
b. Symptomatology depends on interruption of ascending and descending tracts
c. Lesionsto thoracic segments or below: paraplegia
d. Lesions to cervical segments: tetraplegia
e. Lesions above C4: respiratory arrest due to paralysisof diaphragm
Cerebral herniations
a. Subfalcine (cingulate gyrus)
i. Cingulate gyrus is displaced underneath the falx to the opposite side
ii. Compression of anterior cerebral artery
b. Transtentorial (uncal)
i. Uncus of the temporal lobe is displaced over the free edge of the tentorium
ii. Compression of the third nerve
. Pupillary dilatation on the same side . Infarct in dependent territory
iii. Advanced stages:Duret hemorrhagewithin the central pons and midbrain
c. Cerebellar tonsillar
i. Displacement of cerebellar tonsils through the foramen magnum
ii. Compression of medulla: cardiorespiratory arrest
1. Neural tube defects
a. Most common developmental CNS abnormalities
b. Results from defective closure of the neural tube
c. Occurs at the two extremities of the neuraxis
d. Folate deficiency involved in pathogenesis
e. Anencephaly
i. Absence of cranial vault
ii. Incompatible with life-babies die soon after birth
f. Neural tube defects of the spinal cord
i. Spina bifida occulta:bony defect of the vertebral arch
ii. Meningocele:bony defect with outpouching of meninges
Meningomyelocele:defectiveformation of the bony arch with cysticoutpouching
of meninges, spinal cord, and spinal roots
iv. Myelocele:defectivebony arch with complete exposure of spinal cord
v. Significant defects lead to paraplegia and urinary incontinence from birth
Developmental Abnormalities:
Arnold-Chiari malformations
a. Type 1
i. Common, but mostly asymptomatic
ii. Downward displacement of cerebellar tonsils
b. Type 2
i. Most often symptomatic
ii. Faulty craniospinal junction, resulting in small posterior fossa,with
. Downward displacement of cerebellar vermis and medulla
. Compressionof the fourth ventricle
. Obstructive hydrocephalus
. Frequent lumbar meningomyelocele
iii. Frequent association with syringomyelia
Developmental Abnormalities: Syringomyelia
a. Ependymal-lined, CSF-filledchannel parallel to and connected with central canal
(Hydromyelia:central canal is simply dilated)
b. Ninety percent of cases associated with Arnold-Chiari type 2
c. Remaining cases:post-traumatic or associated with intraspinal tumors
d. Syrinx enlarges progressively and destroys the spinal parenchyma
e. Symptomatology: paralysis and loss of sensory functions
Perinatal brain injury
a. Injury to the brain during prenatal or immediately postnatal period
b. Most common cause of cerebralpalsy
c. Most frequent in premature babies
d. Germinal matrix hemorrhage: localized in the germinal matrix due to its fragile
vessels
e. Periventricular leukomalacia
i. Infarcts in watershed areas (periventricular white matter in the fetus)
f. Multicystic encephalopathy: multiple brain infarcts occurring early in pregnancy
Huntington disease (HD)
a. Autosomal dominant disorder characterized pathologically by degeneration of
GABA-nergicneurons of caudate nucleusand clinicallyby choreaand dementia
b. Epidemiology
i. HD affects those of northwestern European descent
ii. No cases are known due to new mutations
iii. Incidence in high-prevalence regions is 1/12,000-20,000
c. Etiopathogenesis
i. HD gene is located on chromosome 4 coding for a protein called huntington
ii. Mutations are due to expansion of an unstable trinucleotide repeat
iii. HD shows features of anticipation and genomic imprinting
Huntington disease (HD): Pathology
i. Gross: atrophy of the caudate nucleus with secondary ventricular dilatation
ii. Histology: loss of small neurons in the caudate nucleus
iii. Pathophysiology: loss of caudate nucleus GABA-nergic neurons removes
inhibitory influences on extrapyramidal circuits, thus leading to chorea
e. clinical manifestations
i. The disease manifests between age 20 and 40.
ii. Chorea: sudden, unexpected, and purposeless contractions of proximal muscles
iii. Changes in personality, marked tendency for suicide, and dementia
f. Diagnosis: genetic diagnosis possible but controversial
g. Treatment: antipsychotic drugs (e.g., haloperidol)
Alzheimer disease (AD)
a. Epidemiology
i. 60% of all cases of dementia
ii. Incidence: 2% at 65 years, doubles every 5 years
iii. Risk factors: aging, significant head trauma,. and familiarity; aluminum:
epiphenomenon, not a risk factor
iv. Protective factors: high level of education, smoking
b. Etiopathogenesis
i. Genetic factors
. 5-10% of AD cases are hereditary, early onset, and transmitted as an autosomal
dominant trait.
Mutations in Alzheimer disease (AD)
Mutations known to cause AD:
Amyloid precursor protein (APP) gene (chromosome 21)
Presenilin-1 gene (chromosome 14): majority of hereditary AD cases
Mutations of presenilin-2 gene (chromosome 1)
AD caused by all of the above mutations is early in onset
Apolipoprotein E gene:
There are 3 allelelic forms of this gene, £2, £3, and £4
The allele E4 of apolipoprotein B (ApoB) increases the risk for AD:
E4 allele is overrepresented in AD patients
£2 is underrepresented; it confers relative protection
AD associated with £4 ApoB allele is late in onset
Trisomy 21:
Virtually all Down syndrome patients are destined to develop AD in their
forties. Down patients have triple copies of the APP gene.
AD: Pathology
i. Accumulation of abnormal proteins intra- and extracellularly
ii. Abnormal proteins
. A beta amyloid: 42-residue peptide from a normal transmembrane protein, the
amyloid precursor protein (APP) . Abnormal tau (a microtubule-associated protein)
iii. Senile plaques: core of ABeta amyloid surrounded by dystrophic neuritic/dendritic
processes and associated with microglia and astrocytes
iv. Neurofibrillary tangles (NFT): intraneuronal aggregates of insoluble
cytoskeletal elements, mainly composed of abnormally phosphorylated tau
forming paired helicalfilaments (PHF)
v. Cerebral amyloid angiopathy (CAA): accumulation of A~ amyloid within the
media of small and medium-size intracortical and leptomeningeal arteries.
CAAmay occur by itself and cause intracerebral hemorrhage.
vi. Additional changes
. Granulovacuolar degeneration (GVD) and Hirano bodies (HBs)
. Developin the hippocampusand arelesssignificantdiagnostically
vii. Lesions involve neocortex, hippocampus, and several subcortical nuclei,
including forebrain cholinergic nuclei (i.e., basal nucleus of Meynert).
. Affected areas are involved in learning and memory
. The earliestand most severelyaffectedarehippocampusand temporallobe
. Small number of SP-NFT also form in intellectually normal aging persons
viii. Macroscopic changes: atrophy of affected regions
. Brains are smaller (atrophic), with thinner gyri and wider sulci
. Hippocampi and temporal lobes are markedly atrophic
AD: Clinical manifestations
i. Insidious onset beginning usually in the seventh or eighth decade
ii. Progressivememory impairment, especiallyrelated to recent events
iii. Alterations in mood and behavior
iv. Progressive disorientation
v. Aphasia (loss of language skills) and apraxia (loss of learned motor skills)
vi. Within 5-10 years, patients become mute and bedridden
e. Treatment
i. No effectivetreatment available
ii. Mild improvement with inhibitors of acetylcholinesterase (e.g., tacrine)
Dementia with Lewybodies
a. Etiopathogenesis: obscure, no known risk factors
b. Pathology
i. The histopathological hallmark is Lewy body (see Parkinsondisease)
ii. Neuron loss accompanies Lewybody formation
iii. Sites involved
. Neocortex, especially the limbic system and cingulate gyrus
. Subcorticalnuclei: basal nucleus of Meynert, amygdala,and substantia nigra
c. Pathophysiology
i. Involvement of neocortex and substantia nigra responsible for cognitive deterioration
and parkinsonism
d. Treatment: possible benefit from cholinesterase inhibitors
e. Clinical manifestations: memory loss, parkinsonism, and visual hallucinations
Amyotrophic lateral sclerosis
a. Degeneration and loss of upper and/or lower motor neurons
b. Usuallymanifests in middle age
c. Loss of upper motor neurons
i. Hyperreflexia
ii. Spasticity
d. Loss of lower motor neurons
i. Weakness
ii. Atrophy
iii. Fasciculations
e. In some cases, involvement of cranial nerve nuclei
f. Clinical diagnosis supported by biopsy of muscles
g. Etiopathogenesis is obscure, but
i. 5-10% of cases are hereditary
ii. A small number due to mutation of the gene encoding zinc-copper superoxide
dismutase on chromosome 21
Friedreich ataxia
a. Autosomal recessive disorder with onset in early childhood
b. Due to expansion of an unstable triplet nucleotide repeat in the frataxin gene
c. Degeneration involvesthe following groups of neurons
i. Dorsal root ganglia
ii. Clarke's column (origin of spinocerebellar tract)
iii. Neurons of posterior column of spinal cord
iv. Cranial nerve nuclei of VII, X, and XII
v. Dentate nucleus and Purkinje cells of cerebellum
vi. Betz neurons of primary motor cortex
d. Clinical manifestations: gait ataxia, dysarthria, hand clumsiness, loss of sense of
position, impaired vibratory sensation, and loss of tendon reflexes. Patients
become wheelchair bound by age 5.
CNS Tumors: Some Features
1. Epidemiology
a. Half of all brain and spinal cord tumors are metastatic
b. Most frequent primary CNS tumors: meningiomas and glioblastomamultiforme
c. Primary malignant CNS tumors account for 2-3% of all cancer deaths in the
United States.
2. Clinical manifestations
a. Headache, often worse at night or early morning
b. Seizures,with tumors involving cerebral cortex
c. Mental changes (e.g., deficits in memory, concentration, reasoning, etc.)
d. Focal neurological symptoms, related to involvement of specific brain regions
e. Symptoms related to increased intracranial pressure
i. Presence of a space-occupying mass within the cranial cavity
ii. Blockageof CSFflow
iii. Edema around the tumor (peritumoral edema)
3. Special features of brain tumors
a. The concept of benign versus malignant neoplasm must be revised; consider
i. Malignant CNS tumors do not metastasize outside the cranial cavity.
ii. Clinical consequences depend on infiltrative behavior and location.
Astrocytomas
a. Originate from astrocytes and exhibit
i. Fibrillary background
ii. Immunoreactivity for glialfibrillary acidicprotein (GFAP)
iii. Diffuse (ill-demarcated) pattern of growth
Fibrillary astrocytomas
i. Gradingis important for both prognosis and treatment. Most frequent systems
in the United States and Europe: Daumas-Duport and WHO
ii. Both systems identify four grades based on nuclear atypia (pleomorphism),
mitoses, necrosis, and vascular endothelial hyperplasia (VEH)
iii. Grade 1-2 astrocytomas are well differentiated astrocytomas
iv. Grade 3 astrocytomas are anaplastic astrocytomas
v. Grade 4 astrocytomas are calledglioblastoma multiforme (GBM)
. GBM is the most cornmon CNS primary J,Ilalignancy
Fibrillary astrocytomas
Histology
Histology: marked nuclear atypia, mitoses, necrosis, and VEH . Characteristic histopathological feature: areas of necrosis surrounded by
rows of neoplastic cells (pseudopalisadingnecrosis)
. VEH is often florid, giving rise to glomeruloidformations
vi. Most common location: white matter, commonly in the centrum semiovale
vii. Well differentiated: affect younger patients and grow slowly
viii. Anaplastic astrocytomas and GBM: aggressive, affect older patients
Pilocytic astrocytoma
Pilocytic astrocytoma
i. Benign astrocytic tumor of children and young adults
ii. Locations: posterior fossa (cerebellum) and diencephalon
iii. Often presents as a cystic lesion with a mural nodule
iv. Histology: spindly neoplastic astrocytes with long bipolar processes; tumors
rich in Rosenthal fibers, thick corkscrew-like eosinophilic structures, which
derive from hypertrophic processes of astrocytes
v. Favorable prognosis for posterior fossa tumors
Oligodendroglioma
a. Glioma of oligodendroglial origin
b. Occurs in 30- to 50-year-old patients
c. Location: white matter of cerebral hemispheres adjacent to neocortex
d. Often manifests with seizures
e. Characteristic histopathology
i. Neoplastic cells are similar to oligodendroglia
ii. Pronounced perinuclear halo: "fried-egg" appearance
iii. Prominent capillary network in a chickenwire pattern
f. Slow-growing tumors that allow long survival (average 5-10 years)
g. Recur after surgery and degenerate into high-grade gliomas over time
Ependymoma
a. Glioma of ependymal origin
b. Location
1. Children: fourth ventricle
ii. Adults: lateral ventricle or spinal canal
c. Gross appearance: circumscribed tumors with papillary architecture
d. Histology: neoplastic cells resemble ependymal cells. Characteristic features:
i. Ependymal rosettes: cells organized around a lumen
ii. Perivascular pseudo rosettes: cells arranged around small vessels
e. Often presents with obstructive hydrocephalus, when present in the fourth ventricle
f. Tend to recur after surgery and acquire more aggressive behavior
Meningioma
a. Originates from meningothelial cells of the arachnoid
b. Tumors of adulthood (women> men), rare in children
c. Gross: attached to the dura, pushes underlying brain without invasion
d. Microscopic
i. Spindle-shaped cells with indistinct borders (syncytial)
Cells arranged in whorls or fascicles
iii. Psammoma bodies frequent
e. May develop at any meningeal site. Most frequent are dural convexities
f. Generally, good prognosis
g. Tumors in some location may not be amenable to complete resection
Primitive neuroectodermal tumors (PNET)
a. Highly undifferentiated; originate from a primordial neuroglial precursor
b. Variably named, depending on location in the brain
c. Most frequent PNETs:medulloblastoma and retinoblastoma
d. All PNETsshare the following features:
i. Develop in children
ii. Histology: blue,small, round cell tumors, with pseudorosettes
iii. Highly aggressivebut responsive to radiation therapy
e. Medulloblastoma arises in the cerebellar vermis (midline location)
i. Grows rapidly and spreads through CSF
ii. Resection and radiation therapy allow 5-year survival of 75%.
Schwannoma
a. Originates from Schwann cells of cranial or spinal nerves
b. Most frequent location: eighth cranial nerve, cerebellopontineangle(CPA)
i. Manifests characteristically with loss of hearing and tinnitus
c. Histology
i. Spindly cells arranged in hypercellular Antoni A areas, alternating with
hypocellular Antoni Bareas
ii. Verocaybodies:parallel rows of neoplastic Schwann cells
d. Neoplastic cells are immunoreactive for a protein called S-100
e. Good prognosis after surgical resection.//
Bilateralacoustic
schwannomasare
pathognomonicof
neurofibromatosis type2.
Craniopharyngioma
a. Arises from rests of odontogenic epithelium within the suprasellar/diencephalic
regIOn .
b. Patients affected are usually children or young adults
c. Contains deposits of calcium evident on x-rays
d. Histology resembles adamantinoma, the most common tumor of the tooth
e. Benign but tends to recur after resection