Thursday, 29 May 2014

Central Nervous System (CNS) Pathology

Hi guys,

Here is the 3rd set of notes in the Pathology series. Please let me know if you like the format of the notes :) Thanks



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Central Nervous System

Congenital Abnormalities

3-4/100,000 live births

Neural Tube Defects

·      Incomplete closure of neural tube
·      Ass. with low pre-conceptual folate
·      Elevated AFP in amniotic fluid and maternal blood

Anencephaly

·      Absence of skull and brain
·      “Frog-eyes”
·      Results in maternal polyhydramnios
o   Baby can’t swallow (no brain) à increased amniotic fluid

Spina bifida

Failure of posterior vertebral arch to close
Ass. with hydrocephalus

Spina bifida occulta

·      Dimple or patch of hair overlying the vertebral defect

Meningocele

Meninges herniation

Myelomeningocoele

Meninges + spinal cord herniation

Cerebral Aqueduct Stenosis

Congenital stenosis of the channel that drains CSF from the 3rd to 4th ventricles
·      CSF accumulates
·      Enlarged head circumference

Dandy-Walker Malformation

Failure of the cerebellar vermis to develop
·      Massively dilated 4th ventricle
·      Absent cerebellum
·      Often with hydrocephalus

Arnold-Chiari Malformation

Extension of the cerebellar tonsils through the foramen magnum
·      Type 1: asymptomatic
·      Type 2: Obstruction of CSF à hydrocephalus
·      Ass with. Myelomeningocele and syringomyelia
·      27yr old man. Cannot feel a burn. Bilateral loss of pain and temperature sensation in upper extremities with preservation of touch and motor. (he has syringomyelia which is ass. with Arnold-Chiari malformation)

Migration disorders

Agyria, pachygyria, polymicrogyria, heterotopias
·      Cause epilepsy and mental retardation

Phakomatoses

Autosomal dominant disorders. Involvement of CNS and skin (neural ectoderm)

Tuberous sclerosis

·      Tubers, adenoma sebaceum, skin pigmentation, hamartomas
MCQ Descriptors:
·      1yr old child with mental retardation, seizures, facial angiofibromas. Repeated episodes of syncope. Cardiac rhabdomyoma. (has cortical tubers)
·      20yr old woman. Mental retardation. Flank pain for 1 week. Right costovertebral angle tenderness. Patches of leathery-appearing (shagreen patches) and hypopigmented (ash-leaf patches) skin were scattered over her body. Subungal nodule on right index finger.. Bilateral renal cysts and tumour masses. Eubependymal nodules and 1-4cm cortical foci with loss of the grey-white distinction. 3cm mass involving interventricular septum. 2 yrs later she has sudden severe headache. Nodule obstructing the cerebral aqueduct. Subependymal giant cell astrocytoma is removed.

Neurofibromatosis

·      Central or peripheral tumours, café au lait spots, axillary freckles

Von Hippel Lindau

·      Rentinal, cerebellar spinal haemangioblastomas, renal tumours
MCQ descriptors:
·      5 yr old child. Retinal angioma.

Spinal Cord Lesions

Syringomyelia

Cystic degeneration of the spinal cord
·      Arises with trauma
·      Ass. with Arnold Chiari malformation
·      Usually occurs at C8-T1
o   Sensory loss of pain and temperature
o   Sparing of fine touch and position sense in Upper extremity (Dorsal column)
·      Knocks out anterior white commissure
·      May extend to anterior horn
o   LMN disorder (Muscle atrophy, weakness, decreased tone, impaired reflexes)
·      May extend to lateral horn
o   Sympathetic input to the face
o   Horner’s syndrome (Ptosis, miosis and anhidrosis)
MCQ descriptors:
·      27 yr old man. Cannot feel a burn. Bilateral loss of pain and temperature sensation in upper extremities with preservation of touch and motor. (he has syringomyelia which is ass. with Arnold-Chiari malformation)

Poliomyelitis

Damage to anterior motor horn due to poliovirus infection
·      LMN disorder (flaccid paralysis, muscle atrophy, weakness, decreased tone, impaired reflexes, negative Babinski sign)
*Polio has a faecal-oral transmission.

Werdnig-Hoffmann Disease

Autosomal recessive degeneration of anterior motor horn
·      Presents as “floppy baby”
·      Death occurs a few years after birth

Amyotrophic Lateral Sclerosis (ALS)

Degenerative disorder of upper and lower motor neurons
·      Anterior motor horn involvement = LMN
·      Lateral corticospinal tract involvement = UMN
*Atrophy and weakness of hands is an early sign
**Lack of sensory loss distinguishes ALS from syringomyelia
·      Most cases are sporadic – middle aged adults
·      Familial cases – zinc-copper superoxide dismutase mutation (normally removes free radicals)

Friedreich Ataxia

Degenerative disorder of cerebellum and spinal cord tracts. Autosomal Recessive. Unstable Trinulceotide repeat (GAA) in frataxin gene (normally needed for mitochondrial iron regulation) à free radical damage via fenton reaction
·      Presents early in childhood
o   Presents as ataxia with loss of vibratory sense and proprioception
o   Muscle weakness in lower extremities
o   Loss of Deep Tendon Reflexes
·      Ass. with hypertrophic cardiomyopathy
MCQ descriptors:
·      Transsynaptic degradation of ipsilateral gracile and cuneate nuclei

Meningitis

Inflammation of the leptomeninges (arachnoid + pia mater)
Common agents:
·      Group B Strep, E coli, Listeria monocytogenes, Streptococcus agalactiae – Neonates
·      N meningitides – Children and Teenagers
·      Strep pneumoniae – Adults and elderly
·      H influenza B – Non-vaccinated infants
·      Coxsackievirus (faecal-oral transmission)
·      Fungi – Immunocompromised
Present with:
·      Headache, neck stiffness and fever
·      Photophobia (esp. with viral cause), vomiting, altered mental status
Diagnosed by Lumbar Puncture (L4/L5):
·      Bacterial
o   Neutrophils with low glucose, positive gram stain and culture
·      Viral
o   Lymphocytes with normal glucose
·      Fungal
o   Lymphocytes with low glucose
Complications are seen with bacterial meningitis:
·      Death (by brain herniation)
·      Hydrocephalus, hearing loss, seizures

Meningococcal meningitis

·      Type A, B & C
·      60% of bacterial meningitis is Type B, 30% type C
·      Vaccine available
·      Droplet infection from nasal carriers
Presents with:
·      Rapid illness, headache, fever, photophobia, neck stiffness.
·      Pus in meninges
Meningeal signs may not develop in Meningococcal Septicaemia:
·      Shock,
·      Haemorrhagic rash
·      Adrenal haemorrhage
·      Waterhouse-Friedrichsen syndrome – adrenal failure due to bleeding into the adrenal glands
Diagnosis by CSF examination and blood culture. *LP is dangerous in ICP is increased.
Complications:
·      Infarction, deafness, blindness, abscess, hydrocephalus, epilepsy

Abscess

Risk factors:
·      Skull fracture
·      Ear/sinus infection
·      Spina bifida, congenital heart disease
·      IV drug use
Often requires surgical drainage
Complications:
·      Rupture into ventricles or subdural space, brain herniation, epilepsy
MCQ descriptors:
·      3yr old child. Severe headaches, two episodes of vomiting. Bilateral papilloedema, impaired level of consciousness, CT shows displacement of ventricles by a multilocular mass with well-defined white high-attenuation rings around black low-attenuation centres. The lesion involves the cerebellum. (Brain abscess most ass. with otitis media)
·      A 56yr old male presents with fever, vomiting and seizures. Examination reveals a well-established ear infection and there is a ‘ring-enhancing’ lesion on the MRI of his brain.
·      A 49 year old male presents with fever, vomiting and seizures. His WCC is increased. He recently had a dental infection. The MRI of his brain shows a ring-enhancing lesion.

TB meningitis, tuberculoma

Blood spread of TB from lung
Basal meningitis with caseating granulomas.
Children and immunocompromised are at risk
Tuberculomas are tumour like masses – rare except in underdeveloped countries
Complication:
·      Cranial nerve palsies, hydrocephalus, infarction
MCQ descriptors:
Mycobacterium tuberculosis 
·      A 42-year-old woman presents with haemoptysis and neck stiffness and photophobia and subsequent impairment of consciousness. On questioning it is revealed that she has been feeling unwell for a couple of weeks. CSF from a lumbar puncture was turbid with a high level of protein (2.3g/L).
·      A 38 year old patient presents to his GP with a headache that has increased over several weeks and has develop a left sided hemiparesis. He is known to be HIV positive.
·      A 40 year old man presents with haemoptysis, neck stiffness and photophobia. He has been feeling unwell for the past week. CSF was turbid with a high level of protein.
·      A 34 year-old known HIV positive male presents with a 4 day history of worsening lethargy and fluctuating consciousness. Neurological examination reveals a palsy of the III and VI cranial nerves. A Ziehl-Nielsen stain of the CSF identifies acid-fast bacilli.

Treponema pallidum

Transient meningitis in early stage. Meningo vascular syphilis in tertiary stage.
·      Dementia, degeneration of posterior columns and cranial nerve palsies may all occur
Gummas tumour like masses are rare
Rare except in homosexuals
Diagnosis by specific serology.

Meningitis by organisms:

Neisseria Meningitidis

MCQ Descriptors:
·      20yr old man. Mild pharyngitis followed a few days later by sudden onset severe headache. Nuchal rigidity. Temp 38.8, pulse 98, RR 26/min. Pus on gross appearance.

Cerebrovascular disease

Neurologic deficit due to cerebrovascular compromise
·      Ischemia (85%), haemorrhage (15%)

Global Cerebral Ischemia

Causes:
·      Low perfusion (atherosclerosis)
·      Acute decrease in blood flow (shock)
·      Chronic hypoxia (anaemia)
·      Repeated episodes of hypoglycaemia (insulinoma)
Clinical Features:
·      Mild – transient confusion with complete recovery (e.g. insulinoma)
·      Moderate – infarcts in watershed areas (end of arteries), damage to hugely vulnerable areas (e.g. 3, 5, 6 pyramidal layers – cortical laminar necrosis)(e.g. damage to pyramidal neurons of hippocampus – memory)(e.g. purkinje layer of cerebellum – cerebellar signs)
·      Severe – death or vegetative state

Ischemic Stroke

Regional ischemia that results in focal neurologic deficits for > 24hrs
Causes:
·      Thrombotic – atherosclerosis – Pale infarction
·      Embolic or venous (usually middle cerebral artery) – Haemorrhagic infarction
·      Lacunar stroke – secondary to hyaline arteriolosclerosis (usually lenticulostriate arteries) – lake shapes in deep structures of the brain
Ischemic stroke leads to liquefactive necrosis
·      Red neurons (early findings, after 12 hrs)
·      Neutophils, microglial cells then granulation tissue
·      Results in fluid filled cystic space surrounded by gliosis (after a month)
TIA < 24 hrs

Intracerebral haemorrhage

Bleeding into the brain parenchyma
·      Classically due to rupture of Charcot-Bouchard microaneurysms, a complication of hypertension, secondary to hyaline arteriolosclerosis
·      Basal ganglia is the most common site
·      Other sites: Brainstem, cerebellum
·      Cerebral amyloid angiopathy (10%) – affects elderly. Frontal and parietal areas. Complication of Alzheimer’s disease
Presents with:
·      Headache, nausea, vomiting and eventual coma
*Haemorrhage into the subependymal germinal matrix leading to intravascular haemorrhage is the major cause of death in premature neonates

Subarachnoid haemorrhage

Bleeding into subarachnoid space
Presents as:
·      Sudden headache “worst headache of my life” with nuchal rigidity
·      Aged 40-60
Lumbar Puncture shows xanthochromia (yellow tinge to CSF)
*Only thing that causes bleed on the bottom of the brain
Cause:
·      Most frequently a rupture of berry aneurysm
o   Anterior circle of Willis (branch points of anterior communicating artery)
o   Ass. with Marfan’s syndrome and ADPKD (autosomal dominant polycystic kidney disease)
MCQ Descriptors:
·      45yr old health man. Developed headaches over the past month. Cerebral angiogram shows a 7mm saccular aneurysm at trifurcation of the right middle cerebral artery. What is the most likely result from this lesion?

CNS Trauma

Epidural Haematoma

Collection of blood between dura and skull
·      Due to fracture of temporal bone with rupture of the middle meningeal artery
·      “Lens” shaped lesion on CT
·      Lucid interval may precede neurologic signs
Complications: lethal hernia
MCQ Descriptors:
·      22yr old male. Following bar fight. Hit on the head with bar club, briefly unconscious, recovered for 1-2 mins and lost consciousness again.

Subdural Haematoma

Collection of blood underneath the dura
·      Rupture of a bridging veins
·      Usually arises with trauma
Presents with:
·      Progressive neurologic signs
·      Acute presentation with rapid increase in intracranial pressure
·      Chronic presentation with personality change, memory loss, and confusion, particularly in elderly
Complications: lethal hernia
MCQ descriptors:
·      Man presents 3 weeks after RTA with confusion and low MMSE score
·      75 yr old woman, fell and hit right side of head. Persistent headache and confusion. Venous haemorrhage.

Herniation

Displacement of brain tissue due to mass effect or increased intracranial pressure
·      Tonsillar herniation – cerebellar tonsils through foramen magnum compressing the brainstem à cardiopulmonary arrest
·      Subfalcine herniation – singulate gyrus herniates under falx cerebri à compresses the anterior cerebral artery à infarction
·      Uncal herniation – uncus of temporal lobe to tentotium cerebeli à compress CNIII (eyes move down and out, dilated pupil), posterior cerebral artery (infarction of occipital lobe), and pulls paramedian artery (haemorrhages on brainstem)

Demyelinating Disorders

Destruction of myelin or oligodendrocytes. Conduction of impulses impaired.

Leukodystrophies

Inherited mutations in enzymes necessary for production or maintenance of myelin

Metachromatic leukodystrophy

Deficiency of arylsulfatase
·      Most common leukodystrophy
·      Myelin cannot be degraded and it accumulates in lysosomes
MCQ Descriptors:
·      12yr old girl. Progressively diminishing neurologic function over 3 years. Difficulty moving, decreased mental ability, incontinence. Brain is atrophic, centrum semiovale and central white matter are shrunken, grey and translucent. Widespread myelin loss with sparing of subcortical U fibres.

Krabbe disease

Deficiency of galactocerebroside B-galactosidase
·      Galactocerebroside accumulates in macrophages

Adrenoleukodystrophy

Impaired addition of coenzyme A to long-chain fatty acids
·      Fatty acids accumulate damaging adrenal gland and white matter

Multiple Sclerosis

Autoimmune destruction of CNS myelin and oligodendrocytes
·      Ass. with HLA-DR2
·      Most common chronic CNS disease of young adults
·      Females > males
·      More commonly seen in regions away from the equator
Clinical Features:
·      Blurred vision in one eye (optic nerve)
·      Vertigo and scanning speech (brainstem)
·      Internuclear ophthalmoplegia (Medial Longitudinal Fasciculus)
·      Hemiparesis or unilateral loss of sensation (cerebral white matter)
·      Lower extremity loss of sensation or weakness (spinal cord)
·      Bowel, bladder, and sexual dysfunction (Autonomic nervous system)
Diagnosis:
·      MRI reveals plaques (grey areas within white matter)
·      Lumbar Puncture
o   Increased lymphocytes
o   Increased Ig with oligoclonal IgG bands
o   Myelin basic protein
Treatment:
·      High dose steroids (Acute attack)
·      Interferon-beta slows the progression
MCQ Descriptors:
·      Increased immunoglobulin, manifesting as multiple oligoclonal bands on electrophoresis in CSF.

Subacute Sclerosing Panencephalitis

Inflammation of grey and white matter.
·      Progressive debilitating encephalitis leading to death
·      Due to slowly progressing, persistent infection of the brain by measles virus
·      Infection occurs in infancy and neurologic signs arise years later
·      Characterised by viral inclusions within neurons (grey matter) and oligodendrocytes (white matter)

Progressive Multifocal Leukoencephalopathy

JC virus infection of oligodendrocytes
·      Immunosuppression (AIDS, leukaemia) leads to reactivation of latent virus
·      Presents with rapidly progressive neurological signs leading to death.

Central Pontine Myelinolysis

Focal demyelination of the Pons
·      Due to rapid IV correction of hyponatremia, particulary in alcoholic or someone with liver disease
·      Occurs in severely malnourished patients
·      Classically presents as acute paralysis (“locked in” syndrome) – can only move eyes.

Dementia and Degenerative Disorders

Loss of neurons within the grey matter.
Degeneration of cortex à dementia (memory loss + cognitive dysfunction without loss of consciousness)
Degeneration of brainstem and basal ganglia à movement disorders

Alzheimer’s disease

Degeneration of cortex.
·      Most common cause of dementia
Clinical Features:
·      Slow-onset memory,
·      Progressive disorientation
·      Loss of learned motor skills and language
·      Behaviour and personality changes
·      Patients become mute and bedridden
·      Focal neurologic deficits not seen early
Sporadic form (majority):
·      Risk increases with age
·      E4 allele of apolipoprotein E is ass. with increased risk
·      E2 ass. with decreased risk
Early onset AD:
·      Familial: Presenilin1 and presenilin 2 mutations on chr 14
·      Downs syndrome (APP gene is on chr 21)
Pathologic Features:
·      Diffuse cerebral atrophy
·      Narrow gyri, widened sulci
·      Dilated ventricles (hydrocephalus exvaccuole )
·      Arritic plaques
·      Cerebral angiod angiopathy (increased risk of haemorrhage)
·      Neurofibrillary tangles (hyperphosphorilated tau protein)
Diagnosis:
·      Presumptive diagnosis made clinically after excluding all other causes of dementia
·      Confirmed at autopsy

Vascular Dementia

Multifocal infarction and injury
·      2nd most common cause of dementia
Due to:
·      Hypertension, atherosclerosis, or vasculitis à causes decreased blood flow to brain

Pick Disease

Degenerative disease of frontal and temporal cortex; spares parietal and occipital lobes. “Pick’s disease picks the frontal and temporal cortex”
·      Round aggregates of tau protein in neurons of cortex
·      Early behavioural and language symptoms.
o   Progresses to dementia

Parkinson’s disease

Degenerative loss of dopaminergic neurons in the substantia nigra pars compacta
·      Common disorder related to aging
·      Unknown aetiology
o   Rare cases related to MPTP (contaminant in illicit drugs)
Clinical Features (TRAP):
·      Tremor (pill-rolling tremor at rest that disappears with movement)
·      Rigidity (cog-wheel)
·      Akinesia/ Bradykinesia (expressionless face)
·      Postural instability and shuffling gait
Pathologic features:
·      Lewy body (alpha synucleian)
*Dementia is a common feature of late disease
** Early onset dementia suggests Lewy body dementia

Lewy body dementia

Characterised by dementia, hallucinations and parkinsonian features with cortical Lewy bodies
MCQ descriptors:
·      60 yr old man, progressive dementia, parkinsonism, visual hallucinations 5 yrs prior to death. Numerous eosinophilic intracytoplasmic inclusions within neurons of substania nigra, limbic cortex, and basal nucleus of Meynert. These inclusions are immunoreactive for ubiquitin

Huntington Disease

Degeneration of GABAergic neurons in caudate nucleus of basal ganglia.
·      Autosomal dominant
o   Expanded trinucleotide repeats (CAG) in huntingtin gene
o   Further expansion occurs during spermatogenesis (anticipation)
Presents with:
·      Chorea
·      Athetosis (slow snake like movements of fingers)
·      Progresses to dementia and depression
·      Suicide is common

Normal Pressure Hydrocephalus

·      Increased CSF results in dilated ventricles
·      Usually idiopathic
·      Can cause dementia in adults
Presents as:
·      Triad of urinary incontinence, gait instability and dementia
*Lumbar Puncture improves symptoms
**Treatment is VP shunt

Spongiform Encephalopathy

Degenerative disease due to prion protein
·      The pathologic protein (B-pleated) is non-degradable and converts the normal form of the protein into additional pathologic forms
·      Damage to neurons and glial cells is characterised by intracellular vacuoles
Aetiology:
·      Sporadic
·      Inherited
·      Transmitted

CJD

·      Most common form of spongiform encephalopathy
·      Usually sporadic (rarely arises due to exposure to prion infected human tissue (e.g. growth hormone or corneal transplant))
Presents as:
·      Rapidly progressive dementia ass. with ataxia and startle myoclonus
·      Spike wave complexes seen on ECG
Results in death in less than 1yr.
MCQ descriptor:
·      55 yr old man. 3 month history of progressive mental deterioration (memory loss, mood changes, error in judgement). Unsteady gait, no history of trauma, seizures, incontinence. CT and LP show nothing. Hypertonicity of all extremities, bilateral equivocal planter response, ataxic gait, myoclonic jerks in lower extremities. (amyloid deposition)

Familial CJD

·      Autosomal dominant
·      Due to mutations or insertions in the prion protein gene on chr 20.

vCJD (variant)

·      Related to exposure to bovine spongiform encephalopathy (“mad cow disease”)

Familial Fatal Insomnia

·      Inherited form of prion disease characterised by insomnia and exaggerated startle response

CNS Tumours

50% metastatic, 50% primary
Metastatic tumours present as multiple, well-circumscribed lesions at grey-white junctions.
·      Lung cancer
·      Breast cancer
·      Kidney cancer
Primary tumours are classified by cell type. Malignant tumours are locally destructive but rarely metastasize.

Glioblastoma Multiforme

Malignant, high-grade tumour of astrocytes
·      Most common malignant CNS tumour in adults
·      Usually arises in cerebral hemisphere,
·      Often crosses the corpus colosum
·      Aka butterfly glioma
·      Pseudopalisading due to necrosis
·      Endothelial cell proliferation
·      GFAP is the intermediate filament present
MCQ Descriptors:
·      55yr old woman, 1yr history of progressive headache and seizures leading to aphagia
·      60yr old man. Extremely aggressive brain tumour, headache, seizures, mental status changes. MRI showed infiltrating neoplasm invading the cerebral hemispheres and crossing the midline. Haemorrhage and pseudopalidase arrangement of tumour cells

Meningioma

Benign tumour of arachnoid cells
·      Most common benign tumour
·      Females > Males
o   The tumour expresses oestrogen receptor
·      Imaging reveals a round mass attached to the dura
o   This compresses (does not invade) the cortex and may present with seizures
·      Whirled appearance
·      Psamoma bodies
MCQ descriptors:
·      50 yr old woman. Neurosurgery for a well-circumscribed intracranial neoplasm attached to dura. It compressed the underlying brain parenchyma without infiltration
·      50 yr old woman. 5 year history of headaches, generalized tonic-clonic seizures, bilateral leg weakness. Skull film reveals hyperostosis of the calvarium. Whirling pattern of cells.
·      40yr old woman. Fully recovers after resection of intracranial neoplasm. Origin in arachnoid cells of meninges.

Schwannoma

Benign tumour of schwann cells.
·      Involves cranial or spinal nerves
o   Esp. CNVIII at cerebropontine angle (CPA)
·      S100 positive
·      Bilateral tumours are seen in neurofibromatosis type 2 (NF2)
Classical present with:
·      Tinnitus, ringing in the ears
·      Deafness
MCQ Descriptors:
·      18yr old female. Decreased vision in left eye for 6 months. Papilloedema on right. She has 14 scatted, 2 to 5 cm flat hyperpigmented skin lesions with irregular borders on the extremities and torso (café-au-lait). Mass in the region of the right optic nerve. Optic nerve glioma is excised. Eight months later she has a mass on the right wrist. [she has neurofibromatosis type 1 – increased propensity for schwannoma]

Oligodendroglioma

Malignant tumour of oligodendrocytes
·      Calcified tumour in the white matter, usually the frontal lobe
·      May present with seizures
·      Fried egg appearance on histology

Pilocytic Astrocytoma

Benign tumour of astrocytes
·      Most common CNS tumour in children
·      Usually arises in cerebellum
·      Cystic lesion with a neuronodule on MRI
·      Astrocytes with thick eosinophilic processes – rosenfall fibres
·      GFAP positive

Medulloblastoma

Malignant tumour derived from granular cells of cerebellum
·      Usually arises in children
·      Derived from neuroectodermal tissue
·      Small, round blue cells (densely packed, poorly differentiated)
o   Homer-Wright rosettes may be present
·      Poor prognosis; tumour grows rapidly and spreads via CSF (drop metastises)
MCQ Descriptors:
·      Child, tumour, cerebellum. Biopsy reveals neural and glial differentiation
·      5yr old boy. Headaches for 1 week. Ataxic gait. Sudden onset of vomiting, comatose. 4cm mass in cerebellar vermis and dilation of the cerebral ventricles. CSF shows small cells with dark blue nuclei and scant cytoplasm

Ependymoma

Malignant tumour of ependymal cells
·      Usually seen in children
·      Most commonly arises in 4th ventricle
o   May present with hydrocephalus
·      Perivascular pseudorosettes
MCQ Descriptors:
·      46yr old woman. Increasing weakness and loss of sensation in the lower extremities for the past 5 months. Unable to walk without assistance. 1x4cm lesion in the filum terminale (spine). Mass is composed of cuboidal cells around papillary cores in a myxoid background.

Craniopharyngioma

Tumours that arise from epithelial remnants of Rathke’s pouch
·      Calcification seen on imaging
·      Benign but tends to recur after resection
Presents as:
·      Supratentorial mass in a child or young adult
·      Optic chiasm compression leads to bitemporal hemianopsia
MCQ descriptors:
5yr old girl. Growth failure. Headaches exacerbated by reading. Papilledema. Mass above and within the sella turcica. Multiloculated cystic and solid tumour containing dark brown, oily fluid. This tumour is thought to arise from epithelial rests of a particular structure (Rathke’s pouch)