Download - Embryonal brain tumours in children
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EMBRYONAL BRAIN TUMORS IN CHILDRENDr. Evith Pereira
Dr. Amruta Padhye Moderator – Dr. D.B.Borkar
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• Cancer in childhood is rare with only 1:600 children developing malignancy by the age of 15 years.
• 20 -25% of childhood tumors are of CNS origin
• This equates to 2.4 cases / 100,000 children per year
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• Medulloblastoma• Atypical Teratoid/ Rhabdoid Tumours• Embryonal Tumors with Multilayered Rosettes• Primitive Neuroectodermal Tumor• Pineoblastoma• Pituitary blastoma
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MEDULLOBLASTOMA
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Introduction
• The origin of Medulloblastoma is from medulla (Latin for marrow), blastos (Greek word for germ) and oma (Greek for tumor);
means “tumor of primitive undeveloped cells located inside the cerebellum”.
• Most common malignant primary brain tumor of child age group.
• First described by Harvey Cushing and Percival Bailey in 1930.
• Initially described as “spongioblastoma cerebelli” - a soft, suckable tumor usually arising in the vermis of cerebellum.
• In 1925, changed name to medulloblastoma - from “medulloblast” - a hypothetical multipotent cell.
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Origin• A highly malignant primary brain tumor that originates in the
cerebellum vermis or posterior fossa.
• Arise in cerebellum and projects into 4th ventricle.
• Originate from embryonal cells k/a medulloblast of cerebellar stem cells. The exact cell of origin, or “medulloblast” has yet to be identified.
• It is currently thought that it arises from Germinative neuroepithelial cells in the external granular layer of cerebellum.
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Epidemiology• Overall account ~ 7% all brain
tumors• 10-20% of brain tumors in pediatric
age group• 0.4%–1% of all adult central
nervous system tumors• 40% of tumors of the posterior
fossa• Peak incidence at the age of 5 –6
yrs In children and 25 yrs in adults
• Approximately 20% of Medulloblastoma present in infants younger than 2 years old;.
• male : female (3:2)
Figure: Distribution of pediatric central nervous system (CNS) tumors by location in the CNS and by tumor type.
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Adult vs. Paediatric MedulloblastomaChild Adult
Usual age ~ 4 - 8 yrs Median age ~ 24 - 30 yrs
Shorter clinical History (~ 3 months) Longer history ( ~ 5 months)
Classical type predominates Desmoplastic type relativelycommoner
Median cerebellar syndromepredominates
Lateral cerebellar syndrome seen
Biologically more agressive Biologically less aggressivePoorer resectability - median location Greater resectability - lateral location
Higher surgical morbidity andmortality
Lower surgical morbidity and mortality - impact of location and age
Poorer RT tolerance Better RT tolerance
Poorer long term survival Better long term survival
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Natural HistoryArising in the midline
cerebellar vermis (roof of the 4th ventricle)
Grows into the 4th ventricle
Fills into the 4th ventricle
Spread around the 4th ventricle
Invasion of ventricular floor
Invasion of brain stem
Invasion of brachium pontis
CSF Spread
Extra neural spread :Young age, males and diffuse subarachnoid disease
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Mode of Spread
• Contagiously- cerebellar peduncle Floor of forth ventricle Ant-brain stem Inf –cervical spine Sup- above tentorium
• CSF(30%) – Intracranially Leptomeninges Spinal cord
• Extraneural (5%) Most common CNS tumor to spread Hematogenous MC sites are Long Bones and Ribs(10-15%) LN(4-6%)
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Pathological Features
Highly cellular tumorHigh N:C ratioCells arranged in typical
Homer - Wright rosettesMultiple histological subtypes
1. Classic medulloblastomas- 70-80%
2. Desmoplastic/nodular- 7%
3. Medulloblastoma with extensive nodularity (MBEN) - 3%
4. Anaplastic
5. Large Cell
WHO classification - 2007
large cell / anaplastic (LCA) 10% to 22%.
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• Gross• Well circumscribed, gray-pink, soft/friable. • well-circumscribedsoft, fleshy tumor with areas of softening & necrosisin the center.
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• Classical Medulloblastoma.• M/E-• Highly cellular • sheets of anaplastic cells with scanty cytoplasm,• hyperchromatic nuclei, that are often elongated & crescent shaped or angulated.• Mitoses- abundant• Occasional Homer-Wright rosettes and perivascular pseudorosettes
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• Homer-Wright rosettes (groups of tumor cells arranged in a circle around a fibrillary center). Similar rosettes are seen in adrenal neuroblastoma.
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• Positive stains• NSE, synaptophysin, Vimentin, Desmin, Nestin• Focal GFAP.• Molecular / cytogenetics description• Isochromosome (17q) or 17p-• 5-30% overexpress c-myc or N-myc;• C-myc overexpression is associated with poor prognosis
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• Differential diagnosis• Lymphoma: diffusely infiltrates CNS until it mixes with normal and reactive
fibrillar cells
• PNET• Ependymoma
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Desmoplasmic/nodular medulloblastoma• nodular b/c of its architecture • desmoplastic because it is permeated by (reticulin) fibers that give it a firm
consistency• M/E-
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• Round pale nodules of tumor separated by zones of darker tumor cells.
• Paler tumor nodules showing a population of uniform round to oval cells on a pale pink fibrillary background.
• The cells have a more mature neuronal appearance and are less active mitotically.
• The surrounding darker tumor cells are more primitive appearing with brisk mitotic activity.
• Desmoplastic medulloblastoma has a better prognosis than the classic form
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Medulloblastoma with extensive nodularity • M/E-• Low power view numerous pale islands• The nodules are composed of a uniform population of tumor cells. The background
is reticulin-free & rich in neuropil-like tissue. Mitosis is not significantly increased. The cells often show streaming in parallel rows
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• Special stain-• Reticulin-rich areas of high cellularity
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• Anaplastic Medulloblastoma • M/E-• Highly anaplastic nuclei • with high rate of mitosis & apoptosis. • Primitive looking cellswith nuclear molding.• Some are composed of large cells with rounded vesicular nuclei (i.e. no nuclear molding). • Poor prognosis.
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Molecular Pathogenesis
Genetic predisposition (syndromes)
MOLECULAR SUBGROUPS
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Genetic predisposition (syndromes)
Gorlin syndrome (3-5 % MB cases)TURCOT SYNDROME (<1 % MB cases)Li-fraumeni syndrome
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GORLIN SYNDROME
The most common syndrome associated with MB (3-5 %).
Autosomal dominant → germline mutation in patched-1(PTCH-
1).
PTCH-1 → over activate SHH pathway.
characterized by nevoid basal cell carcinoma & skeletal
abnormalities.
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TURCOT SYNDROME
Brain tumour (MB) & familial adenomatous polyposis (FAP).FAB caused by autosomal dominant→ inactivation adenomatous
polyposis coli (APC) gene on chromosome 5.
APC is part of protein complex in the WNT signaling
pathway→ control cell proliferation and differentiation.
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LI-FRAUMENI SYNDROME
Mutations in TP53 (17p13). Worse outcome.
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MOLECULAR SUBGROUPS
MB divided into 4 groups based on:DNA copy number, mRNA expression profiles and Somatic copy number aberrations.
1.SONIC HEDGEHOG (SHH) pathway2.WINGLESS (WNT) pathway3. TP 53 mutations4. MYC / MYCN amplification.
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SONIC HEDEHOG (SHH) pathway
Abnormalities in SHH pathway are present
in 30% of MB cases.
MB pathology usually desmoplastic.SHH up-regulate MYCN gene.
Tp53 mutations are present in 10-20 % of
SHH tumours.
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WINGLESS (WNT) pathway
WNT tumours are seen in children and adults. Rarely in infants.It associated with the most favourable
prognosis WNT protein binds to its receptor→
destabilizes APC protein.Loss chromosome 6.
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TP 53 MUTATIONS are present in 10-20% of
WNT and SHH MB and very rarely in the other
subtypes.
MYC / MYCN - amplification of MYC group
genes is associated with a worse prognosis.
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Symptoms & signs
MB patients present with symptoms and signs of:
1. Increased intra cranial tension.
2. Cerebellar dysfunction
Weeks→ few months
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Evaluation
History
Morning headache
Nausea & vomiting
Visual changes
Confusion
Unsteady walking
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A combination of surgery, radiotherapy and chemotherapy
Multi modal approach
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Child AdultUsual age ~ 4 - 8 yrs Median age ~ 24 - 30 yrs
Shorter History (~ 3 months) Longer history ( ~ 5 months)Classical type predominates Desmoplastic type relatively
commonerMedian cerebellar syndrome
predominatesLateral cerebellar syndrome seen
Biologically more aggressive Biologically less aggressivePoorer resectability
(median location)Greater resectability
(lateral location)Higher surgical morbidity and
mortalityLower surgical morbidity and
mortality Poorer RT tolerance Better RT tolerance
Poorer long term survival Better long term survival
Difference in treatment between child & adult
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Treatment at relapse
Relapse occurs in 20 - 30 % following initial treatment.
Site of relapse:
Local→ 1/3 cases
Disseminated (brain and spine)→ 1/3 cases
Both local and disseminated (brain and spine)→ 1/3
Time: within 3 years (children) but late relapse in
(adults).
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Collin’s Law states : • The period of risk for recurrence of embryonal chilhood
neoplasms = age of patient at diagnosis + 9 months.
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Atypical teratoid / rhabdoid tumor
• Comprise 1-2% of all CNS tumours in childhood.• M:F – 1.9:1• Biallelic mutations in the SMARCB1 gene(encodes for INI1)• Infants and young children (mean age 17 months) • Tumours of cerebellum or CP angle• Usually supratentorial (cerebral or suprasellar)• Poor prognosis- Metastatic d/s and young age• Very aggressive with mean survival 11 months post-surgery• Metastasizes throughout CSF.
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•Large and pleomorphic rhabdoid cells with abundant eosinophilic cytoplasm, often filamentous cytoplasmic inclusions and vacuoles •Eccentric round nuclei and prominent nucleolus •May have mucinous background •May have epithelioid features with poorly formed glands or Flexner-Wintersteiner rosettes
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CYTOLOGY DESCRIPTION•Cells are large, round and plasmacytoid or rhabdoid•Also small, round, primitive, neural type cells with high N/C ratio •Apoptotic bodies, mitotic figures, marked necrosis •Variable dystrophic calcification
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GFAP
EMA VIMENTIN
POSITIVE STAINS
Vimentin, EMA, smooth muscle actin
Cytokeratin, neurofilament Focal GFAP, variable
synaptophysin and chromogranin
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DIFFERENTIAL DIAGNOSIS
•Choroid plexus carcinoma
•Composite rhabdoid tumors (with other component, usually INI1+)
•Ependymoma
•Occasional germ cell tumors
•PNET/medulloblastoma
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SUPRATENTORIAL PRIMITIVE NEUROECTODERMAL TUMOR
•Rare tumor, usually cerebral hemisphere •Medulloblastoma like histology•Disseminate along CSF pathway•Usually infants and children •Uniformly small and densely hyperchromatic cells of entirely undiff appearance disposed in patternless sheets •Desmoplastic mesenchymal components, high mitotic rates, necrosis and cystic change.
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Small blue cell tumor with round, hyperchromatic cells, abundant mitotic figures and fibrosis
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With abundant neuropil and true rosettes.
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POSITIVE STAINSCD99 (strong membrane staining) Focal GFAP
DIFFERENTIAL DIAGNOSISAnaplastic glioma Atypical teratoid/rhabdoid tumorCentral PNET/medulloblastomaLymphomaMelanomaRhabdomyosarcoma Small cell meningioma
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EMBRYONAL TUMOURS WITH MULTILAYERED ROSETTES
•Amplification of a miRNA on chromosome 9(C19MC) and over expression of the RNA binding protein LIN28a.
•“Embryonal tumours with abundant neurophil and true rosettes (ETANTR)”
•Ependymomatous rosettes- Multilayered cells surrounding a lumen, patches of dense cellularity and areas of more differentiated tumour with abundant neurophil.
•Poor prognosis with early progression of disease and death.
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Ependymomatous rosettes- Multilayered cells surrounding a lumen, patches of dense cellularity and areas of more differentiated tumour with abundant neurophil
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LIN28A immunohistochemistry of ETANTR
FISH analysis the C19MC 19q13.42 probe (green signals)
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PINEOBLASTOMA
•High Grade IV of IV •Second most common pineal gland tumor after germ cell tumor •Germ line mutations in either RB gene or DICER1•Presents with signs related to location of the tumour in the upper midbrain, with Parinaud’s syndrome (failure of up-gaze, pupils that react poorly to light but respond to accomodation, nystagmus and lid retraction)
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•Hydrocephalus- main presenting complaint
•Usually < 20 years
•Frequent CNS metastases or spinal seeding - main cause of death
•5 year survival approx. 58%
•Poor prognostic factors: 7+ mitotic figures/10 HPF Presence of necrosis No neurofilament staining
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Dense small nuclei and scant cytoplasm Homer-Wright rosettes Sheets of cells with high grade (anaplastic / undifferentiated) features including high N/C ratio with minimal cytoplasm and large hyperchromatic nuclei •Necrosis, mitotic figures •Homer-Wright or Flexner-Wintersteiner rosettes
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Small blue cell neuroepithelial malignant tumor
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Positive stainsNSE, synaptophysin, retinal S-antigen
Differential diagnosisGlial neoplasms: GFAP+
Medulloblastoma
Pineocytoma: better differentiated cells with more cytoplasm, smaller cells, no/rare mitotic figures
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PITUITARY BLASTOMA
•First 2 years of life with Cushing’s syndrome with ophthalmoplegia
•Histopathology- Combi. of epithelial structures, small embryonal cells and secretory cells.
•Express synaptophysin and chromogranin
•High frequency of germ line DICER1 mutations
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