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Neurology > Pediatric Brain Tumor > Flashcards

Pediatric Brain Tumor Flashcards

1
Q

What is the most common pediatric solid tumor? Accounts for how much of childhood cancers?

A

Brain tumors

18-20%

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2
Q

What are the peak ages for CNS tumors?

A

Early childhood and late adulthood

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3
Q

What is the gender predominance in the first decade of life?

A

Male

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4
Q

What location of CNS tumors is the most common in children? Except when?

A

Infratentorial tumors

1st year of life

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5
Q

What type of CNS tumors are more likely to occur in children and young adulthood? Older adulthood?

A

Medulloblastomas, supratentorial primitive nueroectodermal tumors (PNET) and pineoblastomas;
GBMs

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6
Q

What is most common type of CNS tumors in pediatric populations?

A

Astrocytomas followed by PNETs, other gliomas then ependynomas

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7
Q

What the anatomic sites and percent of incidence for pediatric CNS tumors?

A

Supratentorial [30-50%]
Midline [10-15%]
Infratentorial [50-60%]

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8
Q

Location of infratentorial tumors?

A

75% in cerebellum & 4th ventricles

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9
Q

Tumors of Posterior Fossa?

A

Medulloblastoma
Astrocytoma
Brainstem glioma
Ependynoma

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10
Q

Suprasellar Tumors?

A

Chiasmal gliomas

Craniopharyngiomas

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11
Q

Hemispheric tumors?

A

Low-grade astrocytoma

High-grade astrocytoma

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12
Q

What location of CNS tumors do you think of in patients < 1 year? Type?

A

Supratentorial; Gliomas, Teratomas, PNETs, Choriod Plexus

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13
Q

What location of CNS tumors do you think of in patients 1 - 11 year? Type?

A

Infratentorial > supratentorial; Medulloblastoma, Ependymoma, Brainstem gliomas

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14
Q

What location of CNS tumors do you think of in patients > 11 year? Type?

A

Infratentorial = Supratentorial; Gliomas, PNET/Medulloblastoma, Germ cell

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15
Q

Pre-disposing factors for CNS tumors in children?

A

Ionizing radiation
Other tumors (i.e. Kidney, retinoblastoma)
Immune suppression (i.e. Wiskott-Aldrich Syndrome, Ataxia - telangiectasia, AIDs)
Famial conditions

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16
Q

Neurofibromatosis I - tumor type? Cytogenetic features?

A

Optic gliomas, meningiomas, ependymomas; 17q11.2 allelic loss

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17
Q

Neurofibromatosis II - tumor type? Cytogenetic features?

A

Bilateral vestibular schwannomas; 22q deletions/ NF2 gene mutations

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18
Q

Tuberous sclerosis - tumor type? Cytogenetic features?

A

Subependymal giant cell tumors; TS gene map to 9q/16p

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19
Q

Von Hippel-Lindau disease - tumor type? Cytogenetic features?

A

Hemangioblastomas; VHL gene on 3p25

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20
Q

Turcot syndrome - tumor type? Cytogenetic features?

A

Medulloblastomas, glioblastoma multiforme; Germline mutation in APC gene or mismatch repair genes hMLh1 & hPMS2

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21
Q

Cowden - tumor type? Cytogenetic features?

A

Dysplastic ganliocytoma of the cerebellum;

Loss-of-function in PTEN –> hyperactivity of mTOR pathway

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22
Q

Li-Fraumeni - tumor type? Cytogenetic features?

A

Multiple brain tumor types but commly astrocytoma and medulloblastoma; p53 mutation

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23
Q

Nevoid basal cell carcinoma/Gorlin syndrome - tumor type? Cytogenetic features?

A

Medulloblastoma; Mutations in PTCH

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24
Q

Most pediatric brain tumors arise from what?

A

Glia of the brain

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25
Q

Where else can pediatric brain tumors arise from?

A

Primitive nerve cells

Non-neuronal embryonal cells

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26
Q

Clinical presentation the Ped CNS tumor depends on what?

A

Location rather than histology

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27
Q

What is the clinical presentation of those pts with supratentorial tumors?

A

Localizing findings
Seizures
Hemiparesis

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28
Q

What is the clinical presentation of those pts with midline tumors?

A 
Endocrinopathies
Diabetes insipidus
Growth disorders
decreased vision
Visual field deficits
Signs of increased ICP
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29
Q

What is the clinical presentation of those pts with infratentorial tumors?

A

Signs/Symptoms related to increased intracranial pressure

30
Q

What is the clinical presentation of those pts with brain stem tumors?

A

Cranial nerve deficit: Double vision, slurred speech, swallowing disorders, “Crossed-weakness”
Occasional hydrocephalus

31
Q

What is hydrocephalus associated with?

A

Midline brain tumors

32
Q

What causes hydrocephalus?

A

Obstruction in the ventricular system

33
Q

Initial symptoms of hydrocephalus?

A

Early morning intermittent headaches and nausea/vomiting

34
Q

Classic triad of signs/symptoms of ICP?

A

AM headches, nausea & vomiting, and lethargy

35
Q

If a patient presents with what, do you need immediate intervention?

A

Sun-downing eyes —> increased ICP

36
Q

Most common childhood brain tumor?

A

Low grade Astorcytoma

37
Q

Location of low grade astrocytoma?

A

May be either supra or infratentorial

38
Q

Astrocytomas are derived from?

A

Astrocytes

39
Q

Histo of juvenile pilocytic astrocytomas?

A

elongated hair-like projections (pilocytic) and presence of eosiophillic Rosenthal fibers and hyalinization of blood vessels

40
Q

What is the process behind juvenile Pilocytic astrocytomas?

A

Activation of the MAPK pathway

41
Q

How is the MAPK pathway activated in JPA?

A

KRAS or BRAF activation

42
Q

KRAS is activated by what?

A

Pts with neurofibromatosis type 1 lose the inhibitory gene NF1 which leads to activation of KRAS

43
Q

BRAF can be activated through what?

A

v600E mutation

44
Q

BRAF fusion JPAs are typically found where?

A

Cerebellar tumors

45
Q

BRAF v600E mutation JPAs are typically found where?

A

extracerebellar regions

46
Q

NF1 loss JPAs are typically found where?

A

Optic pathway

47
Q

From where do medulloblastomas arise?

A

Primitive nerve cells

48
Q

What is a medulloblastoma found in cerebrum locations called?

A

Primitive neuroectodermal tumor (PNET)

49
Q

What is a medulloblastoma found in cerebellar locations called?

A

Medulloblastoma

50
Q

Peak age of medulloblastoma?

A

3-4 years

51
Q

Male:Female ratio of medulloblastoma?

A

1.5:5

52
Q

Growth speed of medulloblastoma?

A

Rapidly and tend to spread through the CSF

53
Q

Histo of medulloblastoma?

A

Densely cellular, Round, oval or angulated (‘carrot-shaped’), Low vascular density, Homer-Wright rosette.
Hyperchromatic


54
Q

What are Homer-Wright rosettes?

A

Pseudorosettes consisting of tumor cells surrounding a fibrillar area

55
Q

Two most common pathways involved in medulloblastomas?

A

Shh and Wnt pathways

56
Q

Describe the inactive Wnt pathway?

A

Frizzled receptors are inactive and b-catenin is phosphyorylated and bound in a protein complex, which is targeted for proteosomal degradation

57
Q

Describe the active Wnt pathway?

A

Frizzled receptors are active and b-catenin complex is disrupted allowing translocation to the nucleus where it is a transcriptional activator. 


58
Q

Describe the inactive Shh pathway?

A

Ptch receptors inhibit Smoothened receptors preventing Smoothened relocating to the cilium. Some Smoothened receptors undergo endocytosis and are incorporated by endosomes. SuFu binds Gli2 and Gli3, downstream effectors in the cytoplasm and primary cilium. Gli2 is also targeted for degradation through the proteosomal pathway

59
Q

Describe the active Shh pathway?

A

Ptch does not suppress Smoothened, which relocates to the cilium with the aid of Kif7. SuFu no longer binds to Gli2 and Gli3, so Gli2 relocates to the nucleus and is a transcriptional activator. Gli3 is a repressor.

60
Q

What is contraindicated in brainstem glioma?

A

Surgery

61
Q

Symptoms of diffuse intrinsic pontine glioma?

A

Corticospinal long tract signs (weakness or hemiparesis), ataxia, and CN 6,7,8 deficits

62
Q

MRI characteristics of diffuse intrinsic pontine glioma on MRI?

A

Engulfs basilar artery by tumor, diffuse extension into pons

63
Q

From what do ependymoma arise?

A

Ependymal lining of ventricles or central canal of spinal cord

64
Q

Sites of ependymoma?

A

Posterior fossa 60%

Spinal Cord 10%

65
Q

Histo of ependymoma?

A

Perivascular pseudorosettes of glial tumor cells that are radially arranged around the blood vessels and true ependymal rosettes of tumor cells that form a central lumen on their own

66
Q

When is development(axonal growth and synaptogenesis) most rapid?

A

< 3 yrs

67
Q

When does growth and development slow?

A

> 6 yrs

68
Q

When is maturation (degree of myelinization) complete?

A

Puberty

69
Q

Neuropsychological effects of radiation on the developing brain?

A

Intellectual impairment, memory deficits, and inability to acquire new knowledge

70
Q

When is cognitive impairment due to radiation therapy most pronounced?

A

< 4 - 7 yrs of age

Neurology (25 decks)

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