Pediatric Neurosurgical Neuropathology
Brain tumors are second only to
leukemias in children
 Brain tumors are the most common solid
organ tumor in children
 70% of pediatric brain tumors are in the
posterior fossa

– Pilocytic astrocytoma
– Medulloblastoma
– Ependymoma
CNS tumors: pediatric vs. adult

Adults: 70% of tumors are supratentorial
– meningioma
– pituitary adenoma
– High grade astrocytoma
» Anaplastic astrocytoma (grade III)
» Glioblastoma multiforme (grade IV astrocytoma)

Pediatric: 70% in posterior fossa
– pilocytic astrocytoma (cerebellar astrocytoma)
– medulloblastoma
Brain tumors: intro

Intracranial neoplasms
– Primary
– Secondary
» Metastatic
» Local invasion

Tumors of the spinal cord
Primary brain tumors: intro

Primary brain tumors are rare
– 2.5% of all cancer deaths
– Second most common type of tumor in children
– There are over 100 different brain tumors

Most common types
– Astrocytomas (adults and children)
» Grades I-IV
– Medulloblastomas (in children)
» also known as: primitive neuroectodermal tumor-PNET
– Meningiomas (adults)
– Pituitary adenomas (adults)
Clinical presentation

Clinical symptoms depend upon:
– Age, location, and type of tumor and grade

Symptoms may include:
– Increased intracranial pressure
» secondary to obstruction of CSF at aqueduct
» hydrocephalus (infants), headache, papilledema, vomiting
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–
–
–
seizures
focal neurological deficits
hormonal changes (pituitary adenoma)
visual changes (diplopia, field defects)
» Pituitary adenoma - pressure on optic chiasm
CNS tumors: diagnosis


Symptoms prompt neuroimaging
CT and MRI
– intra-axial vs. extra-axial
– Location of tumor
– contrast enhancement
» typical of high grade
» also in some low grade, i.e., pilocytic astrocytomas
CNS tumors: location

Extra-axial
– meningiomas

Cerebral hemispheres
– grade II-III astrocytomas, GBM


Crossing corpus callosum - GBM
optic nerve - pilocytic astrocytoma
– (in Neurofibromatosis Type 1)


Sella - Pituitary adenoma
Peri-III ventricle - Pilocytic astrocytoma, GBM
CNS tumors: location

posterior fossa (in children)
– pilocytic astrocytoma
– medulloblastoma

brainstem (pons)
– pontine glioma (astrocytoma)

spinal cord
– low-grade astrocytomas (grade I and II)
Pilocytic astrocytomas
– Most common in children
– Grade I astrocytoma
– Cerebellum (posterior fossa), optic nerve
» Thalamic, spinal cord, cerebral
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Discrete, well circumscribed mass
Often with associated cystic area
Contrast enhancing
Histologic appearance:
» Biphasic: piloid cells and microcystic areas
» Rosenthal fibers
» no mitoses
Pilocytic astrocytomas
Rosenthal fibers
biphasic
Piloid cells
cyst
Tumor of cerebellum, often with cyst,
biphasic, Rosenthal fibers, piloid
cells (enlongated bipolar)
Astrocytoma - high grade


Astrocytoma grade II and III are very, very rare in the
pediatric population
Grade IV - glioblastoma multiforme
– Most common astrocytoma in adults
– Only about 10% of astrocytomas in children


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Diffusely infiltrating tumor of cerebral hemispheres
Contrast enhancing tumor
Histological appearance:
–
–
–
–
Densely cellular, with marked nuclear pleomorphism
Numerous mitoses
Endothelial proliferation
Necrosis with pseudopallisading
Glioblastoma (grade IV)

Less common in children than adults, typical
pathology (necrosis with pseudopallisading)
Pontine glioma
Diffuse expansion of pons, usually high
grade astrocytoma (III-IV)
Medulloblastomas


PNET of posterior fossa in children
Histologic appearance:
–
–
–
–
–
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Densely cellular “small blue cell tumor”
Numerous mitoses
Apoptotic (karyorrhectic) cells
Endothelial proliferation
Necrosis
neuronal or glial differentiation
» Homer Wright rosettes
» GFAP positive cells
Medulloblastoma


Mass arising in roof of
fourth ventricle
Homer Wright rosettes
Ependymoma


Mass arising in floor of
fourth ventricle
Perivascular
pseudorosettes
Meningiomas

Discrete non-invasive tumor
– Extra-axial, pushes into brain
– Attached to dura
– Hyperostosis or invasion of skull common

Histologic appearance:
– Fibroblastic or menigothelial cells
– Meningothelial whorls
– Psammoma bodies

Rare in children, may be intraventricular
(lateral ventricles)
Meningiomas
Extra-axial tumor, meningothelial cells, whorls and
psammoma bodies
Ganglioglioma
Cerebrum, cervicomedullary, often with cystic component
Increased numbers of neurons (some binucleate) and increased glial cells
(usually astrocytic)
Craniopharyngioma


Heterogeneous, cystic mass in suprasellar region
Basiloid layer, stellate reticulum, “wet” keratin, often
calcified
Choroid plexus papilloma

Lateral ventricle in children (fourth ventricle
in adults)
Germ cell tumors
Germinoma
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Teratoma
Pineal - 99% males, most are germinomas
Suprasellar - often mixed germ cell tumor, 50%
female
Teratomas are rare
Metastatic tumors
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The most common “brain” tumor in adults is
metastatic
Metastatic tumors are rare in children
The most common metastatic tumor in children is
osteosarcoma
Local extension of malignant tumors of vertebral
bodies (Ewing’s sarcoma) or paravertebral soft tissues
(neuroblastoma) are not uncommon
Other tumors

Subependymal giant cell astrocytoma (SEGA)
– Intraventricular tumor in Tuberous sclerosis

Desmoplastic infantile ganglioglioma (DIG)
– Superficial cerebral tumor in infants

Dysembryoplastic neuroepithelial tumor (DNET)
– Hamartomatous lesion associated with seizures

Atypical teratoid rhabdoid tumor (ATR, AT/RT)
– Infants, posterior fossa, very malignant

Eosinophilic granuloma
– A type of Langerhans cell histiocytosis
– Single discrete osteolytic lesion in skull

Meningioangiomatosis
– Hamartomatous superficial cerebral lesion associated with
seizures
Hereditary syndromes

Neurofibromatosis type I
–
–
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–
–
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Café-au-lait spots
Dermatofibromas, multiple
optic nerve astrocytomas, bilateral
plexiform neurofibroma
Malignant peripheral nerve sheath tumor
Neurofibromatosis type II
– bilateral acoustic neuroma
– multiple meningiomas
– ependymomas