TUMORS OF THE CNS

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TUMORS OF THE CNS

• DEPT. OF PATHOLOGY
• 2009

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TUMORS OF THE CNS

• The annual incidence of these ranges from 10 to
  17 per 100,000 persons for intracranial tumors
  and 1 to 2 per 100,000 persons for intraspinal
  tumors
• About 50 to 70 are primary tumors, and the rest
  are metastatic
• Tumors of the CNS account for 20 of all cancers
  in childhood

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TUMORS OF THE CNS

• About 70 of childhood CNS tumors arise in the
  posterior fossa
• A comparable number of tumors in adults arise
  within the cerebral hemispheres above the
  tentorium
• Signs and symptoms related to both local tumor
  growth and secondary effects of edema(vasoge
  nic)
• Tx is often tumor specific
• Varying combinations of surgery/radiation
  therapy
• Chemotherapy-less commonly used(intrathecal)

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TUMORS OF THE CNS

• The term benign is based on histology and does
  not necessarily determine outcome
• Outcome influenced by
• degree of differentiation
• location(relationship w/vital centers)
• surgical resectability
• radio/chemosensitivity

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TUMORS OF THE CNS

• CLASSIFICATION OF BRAIN TUMORS.
• Neuroectoderm derived tumors
• -neuronal differentiation or nerve cell
  origin
• gangliocytoma
• primitive neuroectodermal tumors
• (e.g. medulloblastoma)
• Glial differentiation-gliomas
• astrocytomas
• oligodendrogliomas

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TUMORS OF THE CNS

• CLASSIFICATION
• Mesenchyme derived tumors
• -meningiomas
• -schwannomas
• Ectopically displaced embrionyc cells
• -Germ cell tumors
• Embryonic rests or vestiges
• -craniopharyngioma
• -colloid cysts/enteric cysts
• -chordoma

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TUMORS OF THE CNS

• GENERAL POINTS ON CNS TUMORS.
• Intracranial tumors are second only to leukemia
  as a cause of childhood cancer
• -account for 20 of chilhood cancers
• In adults
• -50 of primary brain tumors are
• gliomas
• -50 of adult tumors are glioblastoma multi
  forme
• -20 of adult tumors are meningiomas

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TUMORS OF THE CNS

• GENERAL POINTS.
• Malignant brain tumors rarely metastasize to
  systemic organs
• Medulloblastoma and ependymomas tend to spread
  via CSF pathways
• Signs/symptoms related to one/several
  combination
• -destruction of neural tissue?specific
  functional deficits
• -irritation of a functional area?seizures

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TUMORS OF THE CNS

• GENERAL POINTS..
• secondary effects of edema/raised intra
  cranial pressure
• -herniation
• subfalcine
• transtentorial
• tonsillar

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TUMORS OF THE CNS

• TUMORS IN THE ADULT.
• Neuroectodermal.
• Astrocytoma
• -low grade
• -anaplastic
• -glioblastoma multiforme

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TUMORS OF THE CNS

• TUMORS IN THE ADULT
• Low grade Astrocytoma.
• Most common in the cerebral white matter
• Accounts for 20 of primary brain tumors
• May contain microcysts/calcium
• Poorly defined margins(infiltrative)
• -relatively uniform proliferating astrocytes in
  a
  fibrillary matrix

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TUMORS OF THE CNS

• TUMORS IN THE ADULT..
• Low grade Astrocytoma
• Morphologic subtypes
• -fibrillary astrocytoma
• -gemistocytic astrocytoma
• -protoplasmic astrocytoma
• Average long term survival -5 yrs
• Tumor progression to more malignant forms is
  not uncommon

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• GLIOBLASTOMA MULTIFORME.
• Most common glioma-50 of gliomas
• Frequently white matter lesion
• Diffusely white matter lesion
• Diffusely infiltrative and may cross midline
  involving
  corpus callosum?butterfly pattern
• Grossly hemorrhagic and necrotic

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• GLIOBLASTOMA MULTIFORME..
• Clinically most aggressive
• Extreme expression of astrocyte anaplasia
• Marked cellular pleomorphism, mitoses, giant
  cells, necrosis and endothelial proliferation
• Mean survival-38 weeks w/surgery and radiation

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TUMORS OF THE CNS

• EPENDYMOMA.
• Ependymal tumor involving the ventricles, most
  frequently 4th ventricle
• -may be associated with obstructive
  hydrocephalus
• -other common sites are spinal cord/filum
  terminale
• More common in childhood
• -20 of chilhood tumors
• -only 5 of adult tumors

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• EPENDYMOMA
• Characteristic feature is the ependymal rosette
  
• Propensity to seed CSF pathways
• Long term cure and survival are exceptional
• Anaplastic variety is much more aggressive

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• MENINGIOMAS.
• 15-20 of primary adult brain tumors
• Occurs in later decades of life
• More common in females
• Arise from arachnoidal cells

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TUMORS OF THE CNS

• MENINGIOMAS..
• Most common sites include
• -parasagital
• -cerebral convexity
• -falx
• -olfactory groove
• -sphenoid ridge
• -suprasellar -foramen magnum

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TUMORS OF THE CNS

• MENIGIOMAS
• Slow growing and benign
• -symptoms include headache,seizures and
  dementia
• -complete surgical excision is curative
• Composed of meningothelial cells
• -arranged in whorls
• -psammoma(calcific)bodies
• May invade cranium(not a sign of malignancy)
  

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• SCHWANNOMA.
• Predilection for sensory nerves
• -most commonly affects vestibular portion
  of 8th cranial nerve
• -cerebellopontine angle mass
• -bilateral acoustic schwannoma is a feature
  of neurofibromatosis(NF) type 2
• -less frequently the 5th nerve is involved
• -other cranial nerves are rarely involved

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TUMORS OF THE CNS

• SCHWANNOMA..
• -Classic histologic features include cellular
  Antoni A, loose myxoid Antoni B areas and
• Verocay bodies
• -Benign, complete surgical excisioncure
• -Malignant transformation is rare

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• PRIMARY CNS LYMPHOMA
• Most are non-Hodgkin lymphomas of B cell origin
• -frequently Burkitts type cell lymphoma
• -T cell lymphomas are rare
• -primary Hodgkins lymphoma is very
• uncommon
• Sporadic(non-AIDS) form seen in elderly
• and immunosuppression states following
• renal transplants, etc
  

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TUMORS OF THE CNS

• PRIMARY CNS LYMPHOMA.
• Epidemic form associated with AIDS
• Usually located deep in the cerebral
  hemisphere
• -frequently multicentric and symmetric
• Does not tend to metastasize to systemic organs
• Sensitive to radiation therapy
• Survival less than 2 years

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• PRIMARY CNS LYMPHOMA.

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• METASTATIC TUMORS.
• Account for approx. 50 of adult CNS
  tumors(very uncommon in chilhood)
• Frequently primary sites include
• -lung, breast,melanoma, kidney,GI tract
• -despite high frequency of colon ca. in
  population,proportion of CNS metasta-
  sis is very low
• -infrequent primary sitesbladder, ovaries,
  uterus
• -metastatic prostatic ca.?vertebra/epidural
  space

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TUMORS OF THE CNS

• CHILHOOD CNS TUMORS.
• All CNS tumor types can be seen in childhood
• Specific subsets of CNS tumors are more common
  in children
• -Medulloblastoma and related primitive
  neuroectodermal tumors(PNETs)
• -Other PNETsneuroblastoma, ependymoblastoma,pi
  neoblastoma

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TUMORS OF THE CNS

• MEDULLOBLASTOMA.
• Most common intracranial tumor of childhood
• -25 of all chilhood tumors
• -arises in the cerebellum
• -presumed origin from external granular layer
  cells
• -peak incidence within the first two
• decades
• -midline vermis is the frequent site in
  childhood

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TUMORS OF THE CNS

• MEDULLOBLASTOMA..
• -composed of undifferentiated small blue
  cells and in 1/3 of cases Homer-Wright
  rosettes(evidence of neuroblastic
  differentiation)
• -CSF seeding is common
• -Tx is by surgery, radiation and chemothera-
  py
• -Despite high-radiosensitivity 5 year survival
• is about 40-60

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• PARANEOPLASTIC SYNDROMES

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