1. Intracranial Pediatric Tumors
Rekha Meesa, MD
University of Michigan
Neuroradiology Fellow
6/9/14

2. Introduction
Childhood tumors account for 15 – 20% of primary brain tumors
CNS tumors are second most common pediatric tumor, exceeded by leukemia
Large studies have shown that posterior fossa tumors and supratentorial tumors occur in near equal frequency
a. Supratentorial tumors more common in first two to
three years of life
b. Infratentorial tumors more common from ages 4 to 10 years of
age.
c. Both locations develop tumors with equal frequency in
children older than 10 years of age

3. Introduction
Symptoms of children with CNS tumors depend on age of presentation
Infants: increasing head circumference, nausea, vomiting, and lethargy
Children: Often same symptoms and signs. Additional symptoms include headache or decreased visual acuity and develop seizures or focal neurological signs.
Tumors in the region of hypothalamus: frequently produce endocrine dysfunction such as diabetes insipidus, growth failure, or precocious puberty.

4. Discussion Posterior Fossa Tumors Brainstem Tumors
Supratentorial Tumors
Sellar and Suprasellar tumors
Pineal Region Tumors
Lymphoma, Leukemia
Metastasis
Extraparenchymal Tumors

5. Posterior Fossa Tumors
Most common posterior fossa tumors of childhood: medulloblastomas, astrocytomas, atypical teratoid/rhabdoid tumors, and ependymomas.
Originate from cerebellar parenchyma and grow into the fourth ventricle

6. Medulloblastoma Highly malignant tumors
Primitive, undifferentiated small, round cells
Most common posterior fossa tumor in children
About two-thirds in children are located in vermis
a. Anteriorly impinges upon roof of fourth ventricle and
causes partial or complete obstruction to CSF flow
Most often in cerebellar hemispheres for adolescents and adults

7. Medulloblastoma: Imaging appearance
Appearance is variable
Tumor location and patient age – most important factors
Most common appearance:
a. Round, slightly lobulated mass
b. Tumors most commonly situated within inferior vermis
c. Restricted diffusion in solid portions
d. Variable enhancement
e. Common location for intracranial mets: vermian and basilar cisterns,
subependymal region of lateral ventricles, subfrontal region.
Drop mets – smooth enhancing coating of spinal cord or enhancing foci in extramedulary,
intradural or intramedullary space

8. Medulloblastoma with leptomeningeal mets

11. Atypical Teratoid/Rhabdoid Tumor
Present at younger age than medulloblastomas (mean age at diagnosis is about 6 years)
In the past, some of these initially diagnosed as medulloblastomas or primitive neuroectodermal tumors (PNETs)
a. Lack of response to standard therapy for
medulloblastomas
Cerebellum most common site of origin
May also arise in cerebral hemispheres, pineal region, septum pellucidum, brainstem and hypothalamus

16. Cerebellar Astrocytoma
Most common brain tumor in children ~ 40 – 50% primary pediatric intracranial neoplasms
About 60% located in posterior fossa (40% in cerebellum, 20% in brainstem)
About 70% of pediatric cerebellar astrocytomas are Juvenile pilocytic astrocytoma ~ Grade 1 by WHO
a. Peak incidence: birth to 9 years of age
About 5 – 15% are anaplastic astrocytomas, more common in older children

17. Cerebellar Astrocytoma: Imaging appearance
Large vermian or hemispheric tumor
a. Predominantly cystic
b. Most have a tumor nodule within the cyst wall
c. Mural nodule shows intense enhancement
d. Enhancement of cyst wall indicates presence of tumor

20. Juvenile Pilocytic Astrocytma

23. Ependymomas 8 to 12% of primary CNS neoplasms in children
8 to 15% of posterior fossa tumors in children
Frequency decreases with age
70% are infratentorial and about 30% are supratentorial
Two age peaks:
a. First between 1 and 5 years
b. Second in mid-fourth decade

24. Ependymomas
Arise from differentiated ependymal cells that line floor and roof of fourth ventricle
Can also arise from ependymal cell rests
Frequently grow out of fourth ventricle and into surrounding cisterns and foramina
15% extend into cerebellopontine angles through foramina of Luschka
60% extend through foramina of Magendie into cisterna magna, foramen magnum and cervical spinal canal
About 20% very soft and deformable, tend to grow through ventricular wall and adhere to surrounding brain
Subarachnoid seeding rare…when present, may represent an anaplastic ependymoma or ependymoblastoma

30. Hemangioblastomas Relatively rare, benign tumors of vascular origin
Less than 20% occur in children
10% associated with von Hippel-Lindau disease
a. Retinal angiomas, multiple cysts or tumors involving
pancreas, liver, kidney and lung
Occur most commonly in cerebellar hemispheres
Spinal cord lesion common associated with syringomyelia
Most common MR appearance: Cystic mass with a vascular mural nodule.
30 – 40% are solid

33. von Hippel-Lindau (VHL)

34. Other tumors of Posterior Fossa and Skull Base
Meningiomas
Langerhans’ cell histiocytosis
Chordomas
Chondrosarcomas

35. Chordoma Rare bone tumor
Arises from remnants of cranial end of primitive notochord
35% intracranial, usually clivus
a. Principal location: sphenooccipital
synchondrosis
b. Other locations: basisphenoid and
basiocciput
50% sacrococcygeal
15% from vertebral body

37. Chondrosarcoma of the petroclival fissure
Extremely rare
Often in paramedian basisphenoid synchrondrosis
Slow-growing.
CT: chondroid matrix mineralization in less than 50% of cases
MRI: heterogenous signal in about 60% cases
Matrix mineralization, fibrocartilaginous elements, or both

39. Brainstem Tumors 15% of all pediatric CNS tumors
Account for 20 – 30% of infratentorial brain tumors
Peak incidence: between 3 and 10 years of age but can be seen at any age
Separated into at least four major categories:
a. Medullary tumors
b. Pontine tumors
c. Mesencephalic tumors
d. Tumors associated with Neurofibromatosis 1

40. Further separations made: focal and diffuse tumors
Majority are astrocytic tumors
a. Focal dorsally exophytic tumors and markedly enhancing
ones are pilocytic astrocytomas (low grade 1 or II).
b. Diffuse, infiltrating type tumors are fibrillary astrocytomas
(grade III or IV)

41. Medullary Tumors Least common site of origin for tumors of brainstem
Young children, signs and symptoms of increased intracranial pressure
Cranial neuropathies, may eventually develop hemiparesis or quadriparesis
Two major categories:
a. Focal dorsally exophytic medullary tumors – sharply
marginated masses, originate dorsal aspect of medulla.
Can extend into vallecula and cisterna magna.
b. Diffuse medullary tumors – infiltrative neoplasms, extend rostrally into pons or
caudally into cervical spinal cord.
Imaging:
Histologically: pilocytic astrocytomas
Low attenuation on CT and very bright on T2 MR images. Inconsistently enhance

42. Pontine Tumors
Most common location of tumors originating in the brainstem
Classic presentation: cranial nerve palsies, pyramidal tract signs and cerebellar dysfunction
Prognosis is poor with 5 year survival rate of about 10% with optimal therapy. Depends on location and aggressiveness of tumor
Diffuse pontine gliomas: high-grade fibrillary gliomas, extremely poor prognosis
More focal, smaller tumors: better prognosis

43. Diffuse Pontine gliomas
Infiltrative masses with expansion of the Pons: majority of pontine gliomas
Hypodense on CT, hypointense on T1 MR images, hyperintense on T2 and FLAIR images
No definite enhancement is seen
Anterior growth results in engulfment of basilar artery

44. Courtesy of Hemant Parmar, MD

45. Courtesy of Ellen Hoeffner, MD

46. Courtesy of Ellen Hoeffner, MD

47. Focal Pontine Tumors Uncommon ~ 10% of pontine tumors
Can be located anywhere within the Pons
Post contrast images demonstrate herterogeneous enhancement

48. Mesencephalic Tumors
Focal
Diffuse
Tectal

49. Mesencephalic Tumors Midbrain second most common site in brainstem
Focal and diffuse tumors
Focal midbrain tumors:
a. treated surgically
b. Focally enlarge affected area. Midline or eccentric
c. Low attentuation on CT, high on T2 images.
d. Post contrast: ring enhancement when tumor is small. Larger tumors show
homogeneous enhancement
Diffuse midbrain tumors:
a. Uncommon
b. Little mass effect, minimal enhancement
c. Chemotherapy/radiation

50. Mesencephalic Tumors Tectal Tumors (tectal gliomas)
a. Extremely benign
b. Typically treated only by CSF diversion, unless tumor
growth is documented
c. Serial/sequential neuroimaging studies are obtained to
look for growth.

53. Brainstem Tumors associated with Neurofibromatosis Type 1
NF1 patients have high incidence of brain tumors with brainstem being a common site of involvement
Medulla most common site
Asymptomatic
Only some show radiological and clinical progression
Some regress
Current recommendation: only ones that exhibit rapid or unrelenting growth should have intervention

54. Supratentorial Tumors
More common than infratentorial lesions in children less than 2 years and older than 10 years
Neonates: Teratoma
Infants: Atypical teratoid/rhabdoid tumors, ependymomas, desmoplastic infantile ganglioglioma and primitive neuroectodermal tumors

55. Hemispheric Astrocytomas
Astrocytomas: most common type of cerebral hemispheric tumor in childhood
Pilocytic Astrocytomas, Astrocytomas, Anaplatic Astrocytmas, Glioblastomas
Hemispheric astrocytomas: similar to cerebellar astrocytomas – solid with a necrotic center or cystic with a mural nodule
Most have a low histologic grade but poorer prognosis than JPAs
Location: deep cerebral hemispheres, basal ganglia or thalamus

56. Astroblastoma Large, hemispheric solid and cystic mass
Often in cerebral hemispheres
Differential Diagnoses
a. Ependymoma
b. Primitive Neuroectodermal Tumor
c. Atypical Teratoid-Rhabdoid Tumor
d. Oligodendroglioma

59. Glioblastoma Multiforme
WHO grade IV
2 types: primary and secondary (degeneration from lower grade astrocytoma)
Peak: years, can occur at any age
Imaging: heterogeneous, hyperintense tumor with infiltration/vasogenic edema
Treatment: biopsy/tumor debulking followed by radiation therapy.

62. Subependymal Giant Cell Astrocytomas
Tumors occur in 5 – 15% of patients with tuberous sclerosis
Grade 1 astrocytomas by WHO
Location: Wall of the lateral ventricle near foramina of Monro and produce hydrocephalus due to obstruction at foramen
Believe to arise from subependymal hamartomas , part of tuberous sclerosis complex

67. Pleomorphic Xanthoastrocytoma
Common in young patients
Often arise peripherally in cerebral hemispheres, involve meninges, good prognosis
Temporal lobe is the most common site (50%) followed by parietal lobe (15 – 20%), frontal lobe (10%) and occipital lobe (5%-10%)
On imaging:
a. well circumscribed peripheral temporal lobe mass
b. Solid portion enhances homogeneously
c. Minimal or absent vasogenic edema

68. Neuronal and Mixed Neuronal-Glial Tumors
Nerve cells and glial cells (astrocytes) are present
Gangliogliomas and Gangliocytomas: uncommon tumors
- 3% of brain tumors in children, 6% supratentorial pediatric
brain tumors
Older children and young adults
Imaging: low density, well-circumscribed lesion with little mass effect or edema, typically within periphery of hemisphere.
Solid, cystic, cystic with mural nodule, or many small cysts

71. Desmoplastic Neuroepithelial Tumors
Desmoplastic Infantile Gangliogliomas (DIG)
Desmoplastic Astrocytomas of Infancy (DACI)
a. Astrocytic and ganglionic cells with desmoplastic stroma
Characterized by presence of astrocytic and ganglionic cells
Usually present in infancy with macrocephaly or partial complex seizures
Imaging: large tumor arising in cerebral hemispheres
- Cysts are quite large, involvement of multiple lobes is common
with predilection for frontal and parietal lobes.
- Peripheral solid component is present which enhances markedly after
administration of contrast

75. Dysembryoplastic Neuroepithelial Tumor (DNET)
Benign masses of cerebral cortex – present as partial complex seizure disorders in children or young adults
DNETs cause as many as 20% of cases of medically refractory epilepsy in children and young adults
Due to marked variability in imaging appearance the best diagnostic criteria for DNET are:
a. Partial seizure disorder beginning before age of 20 years
b. No neurologic deficit or a stable congenital deficit
c. Cortical tumor location

79. Supratentorial Ependymomas
Comprise between 20 – 40% of childhood ependymomas
Occur in males more commonly than females
Histologically identical to infratentorial ependymomas
Half the cases have small foci of calcification. Cystic areas common in larger lesions.
Supratentoiral tumors uncommonly intraventricular
Most common locations: parietal and temporoparietal regions
MRI: major characteristics are heterogeneity and peritrigonal location

80. Tumors with Neuroblastic or Glioblastic Elements: Primitive Neuroectodermal Tumor
Highly cellular tumors composed of greater than 90% to 95% undifferentiated cells
Histologically similar to medulloblastomas, pineoblastomas, atypical teratoid/rhabdoid tumors and peripheral neuroblastomas
Uncommon tumors
Comprise less than 5% of supratentorial neoplasms in children, commonly seen in children under age of 5 years

81. Primitive neuroectodermal tumor
Frequently occur in deep cerebral white matter
Usually quite large at time of presentation
Sharp margins
Necrotic areas and foci of calcification are seen
Typical MR appearance:
a. Large, sharply marginated mass
b. Can be located in either cerebral hemisphere or lateral
ventricle
c. Imaging appearance is variable: Solid to cystic appearance, homogeneous to markedly
heterogeneous to a rim of solid tumor surrounding central necrosis

82. Other tumors Medulloepithelioma
Atypical Teratoid/Rhabdoid Tumors of Infancy and Childhood
Oligodendroglioma
Hamartomas
Plasma Cell Granulomas

83. Oligodendroglioma

85. Germ Cell Tumors
While most found in the suprasellar and pineal regions, siginificant number 4 – 14% arise in basal ganglia and thalami
MRI: heterogeneous, poorly marginated tumors, round or lobulated, little mass effect

86. Meningioangiomatosis
Rare, benign hamartomatous lesions, can be seen in association with NF2
Involves cerebral cortex and often overlying leptomeninges
Pathologically: cortical meningovascular fibroblastic proliferation and leptomeningeal calcification
Imaging:
CT: peripheral hyperdense mass with edema in the adjacent white
matter. Calcifications and cysts may be present
MRI: heterogeneous masses, iso- to hypointense compared to gray
matter on T1-weighted images and hypointense with hyperintense periphery on
T2-weighted images. Demonstrate heterogeneous enhancement

87. Sellar and Suprasellar Tumors
Craniopharyngioma
Astrocytoma/Germ Cell tumors
Langerhans cell histiocytosis
Hypothalamic hamartoma
Arachnoid cyst
Suprasellar pituitary adenoma
Rathke cleft cyst
Lymphocytic hypohysitis
Granuloma
Medulloepithelioma

88. Chiasmatic/Hypothalamic Astrocytomas and Optic Nerve Tumors
Gliomas of optic chiasm enlarge and involve hypothalamus
Astrocytomas in hypothalamus grow anteriorly or inferiorly to involve chiasm.
Astrocytomas of optic chiasm and hypothalamus make up 10 – 15% of supratentorial tumors in children.
Most common symptom of diminished visual acuity
Optic atrophy and endocrine dysfunction are also seen

89. Suprasellar Glioma

92. Chiasmatic/Hypothalamic and Optic Nerve tumors
About 20 – 50% of patients with astrocytomas of optic chiasm/hypothalamus have clinical evidence or positive family history of NF1.
When optic nerve is involved, affected nerve expands in a fusiform fashion
Tumors originating within the optic nerve grow very slowly and histologically classified as juvenile pilocytic astrocytomas.
Optic pathway tumors may involute spontaneously
Growth potential of pilocytic astrocytomas decreases progressively with age
Tumors originating in optic chiasm and hypothalamus may have higher histologic grade

93. Craniopharyngioma Remnants of craniopharyngeal duct
Arise anywhere along pituitary stalk, from floor of third ventricle to pituitary gland
Account for 3% of intracranial tumors (15% of supratrentorial tumors and 50% of suprasellar tumors in children)
Incidence peaks between 10 and 14 years of age, second peak in fourth to sixth decades of life

94. Craniopharyngioma
Divided into two histologic types: adamantinomatous and papillary types
Adamantinomatous types:
a. Lobulated masses with multiple cysts often encase the
vessels of the Circle of Willis
b. Commonly calcify and more likely involve the
hypothalamus
Papillary craniopharyngiomas
a. Often present in adults
b. Predominantly solid, originate mostly in sella

95. Frequently suprasellar in location
90% will have a cystic component, 90% will be partially calcified and 90% enhance
Differential Diagnosis:
a. Rathke cleft cysts
b. Hemorrhagic Pituitary adenomas

99. Hypothalamic Hamartomas
Rare congenital malformation, composed of normal neuronal tissue
Located in region between mamillary bodies and tuber cinereum of hypothalamus
Boys > girls
Common presenting symptoms:
a. Precocious puberty
b. Epilepsy – gelastic type (“laughing seizures”)

100. Hypothalamic Hamartomas
Well-defined round to oval masses, project from floor of third ventricle into suprasellar or interpeduncular cistern
Imaging:
a. CT: Isodense to brain tissue
b. MRI: heterogeneous on T1 and T2 images
c. No enhancement on post contrast images

102. Langerhans’ Cell Histiocytosis
Most common intracranial manifestation: pituitary stalk involvement
Diabetes insipidus develops, presents in 5% of patients with LCH at presentation.
Starts with development of granulomas in subarachnoid space, with subsequent invasion of hypothalamus and infundibulum
Pituitary Stalk and hypothalamus:
a. Mild thickening of infundibulum to frank hypothalamic
mass
b. Differential diagnosis: germ cell tumors, lymphocytic
hypophysitis, lymphoma, and granulomatous diseases
(tuberculosis and sarcoidosis)

103. Pediatric Pituitary Tumors
Uncommon
Pituitary Macroadenomas more common than microadenomas

104. Rathke Cleft Cysts Epithelium-lined cysts
Arise primarily in sella turcica and contain mucoid material
Thought to derive from remnants of Rathke’s pouch
Maybe embryologically related to craniopharyngiomas
May produce symptoms by compression of pituitary gland or suprasellar structures
Imaging:
a. CT: round or lobulated intra- or suprasellar mass with attenuation values similar to CSF
b. MRI: sharply defined mass, usually lies between anterior and posterior pituitary lobes,
or anterior to the pituitary stalk. Variable signal intensity and no enhancement.
c. Can become infected, leading to a pituitary abscess.

105. Courtesy of Ashok Srinivasan, MD

106. Courtesy of Hemant Parmar, MD

107. Pituitary Apoplxey a. Acute clinical syndrome with headache,
visual defects, altered mental status
b. Hemorrhage or infarction of pituitary gland
c. Pre-existing pituitary macroadenoma
Diff Dx:
a. Pituitary macroadenoma
b. Craniopharyngioma
c. Rathke cleft cyst

110. Lymphocytic Hypohysitis
Autoimmune inflammatory infiltration of pituitary gland by lymphocytes and plasma cells
Leads to destruction of gland
Two forms
a. Adenophypophysitis – anterior pituitary gland
b. Infundibuloneurohypophysitis – primarily posterior
pituitary gland, infundibulum and hypothalamus
MRI: Enlarged hypothalamus, infundibulum, and pituitary gland.

111. Suprasellar Germ Cell Tumors
Originate in hypothalamus and grow into infundibulum
a. Cause diabetes insipidus
Germinomas, most common histological type
Imaging characteristics vary
a. Small: thickening of infundibulum and uniformly
enhancing after administration of contrast
b. Large: homogeneous masses of gray matter attenuation –
uniformly enhance after contrast adminstration

114. Pineal Region Masses Germ Cell Tumors Germinomas Choriocarcinoma
Embryonal Cell Carcinoma
Endodermal Sinus Tumors
Pineal Parenchymal Tumors
Pineocytomas
Pineoblastomas

115. Germinomas Most tumors are germ cell tumors
Comprise about 3% to 8% of pediatric brain tumors
More common among Asian populations – 10% of pediatric brain tumors
a. 65% are germinomas
b. 26% are nongerminomatous (16% teratomas, 6%
endodermal sinus tumors or embryonal cell carcinoma,
4% choriocarcinomas)
c. 9% are mixed

116. Pineal Region Germinomas
Occur in second and third decades of life
10:1 male predominance
Presentation:
a. Hydrocephalus (compression of aqueduct of Sylvius)
b. Parinaud syndrome (paralysis of upward gaze) due to
compression of mesencephalon (midbrain)
c. Metastatic spread occurs early and frequently via CSF
giving the brain a sugar-coated appearance

118. Pineal Parenchymal Tumors
Pineocytomas
Pineoblastomas
Both arise from pineal parenchymal cells
Less common than pineal germ cell tumors

119. Pineocytomas Affect both sexes equally Very rare
Mature cells, circumscribed, non-invasive, slow growing
Natural history is not well defined because they are very rare
a. Some remain circumscribed and non-invasive
b. Others metastasize extensively

120. Pineoblastomas
Primitive, small round cell tumors – highly cellular and resemble medulloblastomas
Demonstrate local invasion as well as distant spread through cerebrospinal fluid
More common in pediatric age group

123. Other pineal region lesions
Dermoids, Epidermoids, Teratomas
Gliomas
Pineal Cysts

124. Teratomas Pineal region most common site
Other sites include parapineal region or suprasellar region
More common in first year of life (neonate & infant period)
Pineal and suprasellar teratomas – marked male predominance
Symptoms: hydrocephalus, parinaud syndrome, and hypothalamic symptoms

126. Leukemia/Lymphoma Most common finding in leukemia
a. Enlargement of ventricles and sulci
Ventricular enlargements represents hydrocephalus, not atrophy
Brain involvement
a. CT: masses iso-hyperdense signal prior to contrast
administration
b. Enhance uniformly after contrast administration
c. MR: slightly hypointense with respect to brain, hyperintense on
FLAIR and T2 sequences with prominent enhancement.

128. Metastasis
Uncommon in the pediatric population

130. Extraparenchymal Tumors
Choroid Plexus Tumors
a. Choroid plexus papillomas and carcinomas rare
b. Arise from epithelium of choroid plexus in both children
and adults

131. Choroid Plexus Papillomas
Often found in first year of life
Severe hydrocephalus
Marked male predominance

132. Choroid Plexus Carcinomas
30 – 40% of choroid plexus tumors in children
Children usually present within first three to five years of life
Focal neurological deficits from local brain involvement
Still present with signs and symptoms of hydrocephalus
a. Lateral Ventricle more commonly involved
b. Third and fourth ventricles less commonly involved
Differentiation between papilloma and carcinoma is histological

134. Extraparenchymal Tumors
Schwannomas

135. Neurofibromatosis type 2

139. Tumors of the Meninges Uncommon in childhood
Comprise only 1 – 2% of primary brain tumors
Presence of a meningioma in a child – raise suspicion for NF2. Search for other meningiomas or schwannomas
Meningeal tumors of childhood
(meningiomas, plasma cell granulomas, meningeal fibromas
and myofibromas, meningeal sarcomas, malignant fibrous
histiocytomas)

142. Embryonic Tumors
Epidermoids
Dermoids
Enteric Cysts

143. Focal fat in the suprasellar region
Inclusion ectodermal tissue in CNS
Epidermoid – squamous epithelium
Dermoids – squamous epithelium and dermal appendages
Differential: Lipoma, Teratoma

144. Ambien Cistern dermoid/lipoma

146. Arachnoid Cyst

149. Brain Tumors in first year of life
Histologic distribution of primary brain tumors in the first year of life is different than the entire pediatric period
Most common brain tumors in the first year of life:
- Teratoma
- Suprasellar astrocytoma
- Atypical teratoid/rhabdoid tumors
- Ependymomas
- Choroid plexus tumors
- Medulloblastoma
- Primitive neuroectodermal tumor

150. References
Barkovich, JA ‘Pediatric Neuroimaging’, fourth edition