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Flashcards in Pediatric Brain Tumors Deck (45):
1

Brain Tumors in Children: Epidemiology

-most common pediatric solid tumor accounting for 18-20% of all childhood cancers
-2nd most common malignancy after leukemia
-most common in 1st decade of life
-2,200 cases/year or 3.3 cases per 100,000
-survival to adulthood is 65%
-2 peaks early childhood + late adulthood (8th decade)
-infratentorial tumors most common in children except in 1st year of life
-male predominance in 1st decade

2

Brain Tumors Children Histology

-embryonal histology is seen more commonly in 1st decade than in adults
-Medulloblastomas, supratentorial primitive neuroectodermal tumors (PNET) & pineoblastomas occur almost exclusively in children & young adults
-High grade gliomas (glioblastoma multiforme) are rare in the pediatric age group

3

Most common CNS tumors in Pediatrics?

-Astrocytomas
then PNETs, other gliomas, then ependymomas

4

Site of Pediatric Brain Tumors

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

5

Brain Tumor Distribution & Age

11 yrs Infratentorial (supratentorial) Gliomas, PNET/Medulloblastoma, Germ cell

6

Pre-disposing factors for Brain Tumors

-Ionizing Radiation
-Other tumors (Kidney, Retinoblastoma)
-Immune Suppression (Wiskott-Aldrich Syndrome, Ataxia-Telangiectasia, Acquired Immunodeficiency)
-Familial Conditions

7

Origins of Pediatric Brain Tumors

-Most arise from the supporting cells of the brain (glia) and are called "gliomas"
-Others arise from the primitive nerve cells, that are much more common in children than in adults
-A 3rd type of childhood brain tumor arises in the non-neuronal embryonal cells

8

WHO Classification of Glial Tumors

-Astocytomas
-Oligodendrogliomas
-Ependymal Tumors
-Choroid Plexus Tumors
-Mixed Gliomas
-GBM

9

WHO Classification of Neuronal Tumors

-Gangliocytoma
-Anaplastic ganglioma

10

WHO Classification of Primitive Neuro Ectodermal

-PNET
-PNET with differentiation
-Medulloepithelioma

11

WHO Classification of Pineal Cell Tumors

-Pineocytoma
-Pineoblastoma

12

Clinical Presentation of Brain Tumor

-Varied
-Location rather than histology

13

Clinical Manifestations of Pediatric Brain Tumors: Supratentorial

-Localizing Findings: seizures, Hemiparesis

14

Clinical Manifestations of Pediatric Brain Tumors: Midline (Hypothalamic/Optic, Craniopharynioma, Pineal)

-Endocrinopathies: (Diabetes insipidus, Growth disorders, Dec. vision, Visual field deficits)
-Signs of inc. ICP

15

Clinical Manifestations of Pediatric Brain Tumors: Infratentorial

-Signs & Symptoms related to inc. intracranial pressure

16

Clinical Manifestations of Pediatric Brain Tumors: Brain Stem

-Cranial Nerve Deficit: (double vision, slurred speech, swallowing disorders, "crossed-weakness")
-Occasional Hydrocephalus

17

Hydrocephalus

-associated with 80% of midline brain tumors
-due to obstruction in ventricular system
-Initial symptoms are early morning intermittent headaches & nausea/vomiting
-most resolve after mass resection, but 15% require placement of shunt or ventriculostomy
-complications include shunt failure, infection or hemmorhage

18

Ocular Pathology of Tumors

-Proptosis or ptosis

19

Papilledema

-blurring of optic disc margin with increased ICP

20

Signs & Symptoms of ICP

Triad: AM headaches, Nausea/Vomiting, Lethargy
-bulging fontanelle, sundowning of eyes, CN 6 palsy, HA/N/V
-1/3 post. fossa tumor patients will require permanent VP shunts following surgical debulking
-presentation before diagnosis is 4-6 months

21

Tumor Diagnostic Evaluation

-H&P (neuro exam)
-Diagnostic Imaging (CT, MRI, MRA, MRS)
-Tissue Diagnosis (surgical biopsy, surgical resection, CSF cytology)
-Metastatic evaluation (CSF evaluation, bone scan, bone marrow aspirates)

22

MRI

-preferred diagnostic study
-easy manipulation of image plane
-avoidance of ionizing radiation
-sensitive to acute, subacute, & chronic blood products
-expensive
-lengthy exam often requiring sedation or anesthesia

23

CT

-fast
-useful in emergent situations
-less expensive

24

Low Grade Astrocytoma

-most common childhood brain tumor
-40% of all CNS tumors
-may be supra or infratentorial
-derived from astrocytes, which are major supportive cells
-astrocytes constitute 40% of CNS cell population & are widely spread throughout the CNS including the optic nerves

25

Astrocytoma: Grading

-low grade are I & II which are histologically benign
-grade III (anaplastic astrocytoma) & IV are malignant (glioblastoma multiforme)
-high grade gliomas represent 7-11% of all CNS tumors

26

Low Grade Astrocytoma Treatment

-primarily a surgical disease
-greater than 75% 5 year survival if gross total resection achieved (90% 5 yr survival and >70% 20 year survival
-chemo/radiation options in those with residual tumor or recurrent disease

27

Juvenile Pilocytic Astrocytoma

-can be in optic pathway
-can be seen with solid & cystic components
-contrast enhancing tumor
-elongated hair-like projections from neoplastic cells
-presence of eosinophillic Rosenthal fibers & hyalinization of blood vessels

28

Juvenile Pilocytic Astrocytoma

-driven by an oncogenic process activating the MAPK pathway
-KRAS activation, BRAF activation with either duplication of c's 7 or v600E mutation causes activation of BRAF
-patients with NF1 have loss of inhibitory gene NF1 causing KRAS activation

29

Pilocytic Astrocytoma Mutations

-BRAF fusion - in cerebellar tumors
-BRAF V600E mutation - extracerebellar regions
-NF1 loss - in optic pathway tumors

30

Medulloblastoma

-20% of all CNS tumors (40% of posterior fossa tumors)
-more common in children than adults
-arise in primitive nerve cells
-cerebrum location (primitive neuroectodermal tumor PNET))
-cerebellar location: medulloblastoma
-peak age is 3-4 years
-male to female 1.5:1

31

Medulloblastoma: Prognostic Factors

-age
-histology
-size at diagnosis
-metastatic spread
-extent of resection
-neurotrophin-3 receptor, TrkC, ErbB2, ErbB-4, C-myc overexpression

32

Medulloblastoma: Treatment

-malignant WHO grade IV grow rapidly & tend to spread through the CSF
-often infiltrate adjacent brain structures preventing total resection
-surgery with craniospinal radiation
-Adjuvant chemotheraphy beneficial (especially in infants & in desseminated or recurrent disease)

33

Medulloblastoma: Microscope

-densely cellular, round, oval or angulated "carrot-shaped"
-low vascular density, Homer-Wright rosette = pseudorosettes consisting of tumor cells surrounding a fibrillar area
-hyperchromatic

34

Medulloblastoma: Pathogenesis

-Wnt pathway - good prognosis
-Shh (PTCH mutation) pathways - good in infants, intermediate in rest

35

Brainstem Glioma

-15% of all CNS tumors
-surgery contraindicated
-uniformly fatal in 18-24 months & <10% 5 year survival
-radiation therapy provides temporary improvement
-supportive care

36

Diffuse Intrinsic Pontine Glioma

-8-10% of all pediatric CNS tumors
-prognosis dismal, median survival from 9-11 months, only 20% past a year
~7 y/o
-symptoms: corticospinal long tract sighs (weakness or hemiparesis), ataxia, CN 6, 7, 8 defects (difficulty w/lateral gaze)
-diagnosis by MRI (engulfs basilar artery by tumor, diffuse extension into pons
-Treatment: not resectable, radiation helps prolong life

37

Ependymoma

-9% of all CNS tumors
-highest incidence in 1st 7 yrs of life, 1:1 M:F
-arise from ependymal lining of ventricles or central canal of spinal cord
-Posterior Fossa 60%
-Spinal Cord 10%

38

Ependymoma Microscope

-Classic (WHO II) exhibits perivascular pseudorosettes of glial tumor cells that are radially arranged around the blood vessels
-also true ependymal rosettes of tumor cells that form a central lumen on their own

39

Ependymoma action

-50% of patients are <5yr at presentation
-tumors are locally invasive
-CNS dissemination is 7-10%
-may be low grade or anaplastic
-PNET variant is called ependymoblastoma
-staging should include CSF examination & spinal MRI

40

Ependymoma Prognostic Factors

-surgical resection
-brain stem involvement
-age
-stage at presentation

41

Treatment of Brain Tumors

-surgery
-radiation
-chemo

42

Surgery

-primary treatment modality
-curative alone in only 20% of cases
-goals - established histologic diagnosis reduction in tumor burden
-extent of resection & outcome
-notable exception: diffused brain stem gliomas

43

Radiation Therapy

-volume & dosage vary according to the histologic diagnosis
-localized treatment unless high likelihood of neuraxis dissemination
-medulloblastoma/PNET
-age & radiation

44

Radiation & the Developing Brain

-development (axonal growth & synaptogenesis) is most rapid in first 3 years of life
-rate of growth & development slows after age 6
-maturation (degree of myelinization) isn't complete until puberty
-want to wait till after 3 but 7 is even better
-effects delayed months to years after treatment
-Neuropsychological effects: intellectual impairment, memory deficits, & inability to acquire new knowledge
-Cognitive impairment is most pronounced in kids younger than 4-7

45

Which is more common: infratentorial or supratentorial?

-infratentorial