Your Visual Guide Medulloblastoma

Understand this diagnosis through data, infographics, and evidence based on modern classification and current research.

~500
New Cases per Year in U.S. (Children)
Understanding Medulloblastoma
What Is Medulloblastoma & How Is It Classified?
Medulloblastoma is the most common malignant brain tumor in children, arising in the cerebellum. WHO 2021 classifies it into four molecular subgroups (WNT, SHH, Group 3, Group 4) with distinct biology and prognosis.
Posterior Fossa Tumor
Molecular Subgroup?
WNT
WNT (~10%)
Best prognosis (~95% OS)
CTNNB1 mut Monosomy 6
SHH
SHH (~30%)
TP53 status determines risk
TP53-wt (good) TP53-mut (poor)
Group 3
Group 3 (~25%)
Worst prognosis, MYC-driven
MYC amplified Large cell/anaplastic
Group 4
Group 4 (~35%)
Most common, intermediate
i17q KDM6A loss
Tumor Grading
WHO 2021 Molecular Subtypes
Medulloblastoma is classified by molecular subgroup, each with distinct biology, demographics, and prognosis.
1
WNT-activated
Best prognosis (~95% survival). CTNNB1 mutations, monosomy 6. Rarely metastatic. Older children and adolescents.
2
SHH-activated, TP53 wild-type
Good prognosis. Includes desmoplastic/nodular variant in infants. PTCH1/SUFU/SMO mutations. Responds to SMO inhibitors.
3
SHH-activated, TP53 mutant
Poor prognosis. Frequent in adolescents/young adults. MYC amplification, chromothripsis. Li-Fraumeni syndrome association.
4
Group 3
Worst prognosis. MYC amplification, large cell/anaplastic histology. Predominantly male infants/children. High metastatic rate.
5
Group 4
Most common subgroup (~35%). Intermediate prognosis. Isochromosome 17q, KDM6A mutations. Predominantly male.
Molecular Markers
The Key Biomarkers
Modern classification depends on specific molecular markers. Each reveals something different about the tumor.
Diagnostic
CTNNB1
Beta-Catenin
Nuclear accumulation defines WNT subgroup. Somatic mutations in exon 3. Excellent prognostic indicator.
WNT subgroup
Prognostic
TP53
Tumor Protein p53
Mutations in SHH subgroup confer significantly worse prognosis. Associated with chromothripsis and Li-Fraumeni.
SHH prognostic
Predictive
PTCH1
Patched 1
Loss-of-function mutations activate Hedgehog pathway. Predicts response to SMO inhibitors like vismodegib.
SHH subgroup
Prognostic
MYC
MYC Proto-oncogene
Amplification defines high-risk Group 3 tumors. Associated with large cell/anaplastic histology.
Group 3 marker
Prognostic
MYCN
N-MYC
Amplification in SHH subgroup associated with worse outcomes. Found in ~5-10% of medulloblastomas.
SHH/Group 4
Diagnostic
OTX2
Orthodenticle Homeobox 2
Amplification/overexpression in Group 3 and Group 4. Transcription factor regulating cerebellar development.
Group 3/4
Diagnostic
KDM6A
Lysine Demethylase 6A
Loss-of-function mutations in Group 4, located on X chromosome. Explains male predominance.
Group 4
Diagnostic
SMARCA4
SWI/SNF Chromatin Remodeler
Mutations in Group 3 and 4. Part of SWI/SNF chromatin remodeling complex.
Group 3/4
Signs & Symptoms
Medulloblastoma Signs & Symptoms
Medulloblastoma symptoms typically relate to posterior fossa mass effect and hydrocephalus. Onset can be rapid.

Posterior Fossa

Headache (often morning), nausea, vomiting from increased intracranial pressure due to hydrocephalus.

Cerebellar

Ataxia, unsteady gait, poor coordination, tremor, dysmetria.

Brainstem Compression

Cranial nerve palsies, double vision, facial weakness, swallowing difficulty.

Spinal Metastasis

Back pain, leg weakness, sensory changes, bladder dysfunction from drop metastases.

Cognitive/Behavioral

Personality changes, academic decline, irritability, especially in young children.

Hydrocephalus

Increasing head circumference (infants), papilledema, altered consciousness.

Diagnosis
The Diagnostic Journey
From first scan to molecular classification — the path to a medulloblastoma diagnosis.
1

MRI Brain & Spine

Brain MRI reveals posterior fossa mass; spine MRI for staging (drop metastases)

2

CT Scan

Shows hyperdense mass with calcification; useful in emergency setting

3

CSF Cytology

Lumbar puncture for staging; positive cytology indicates leptomeningeal spread

4

Surgical Resection

Maximal safe resection via posterior fossa approach for tissue diagnosis

5

Neuropathology

WHO grading, histologic subtype (classic, desmoplastic, LCA, MBEN)

6

Molecular Profiling

DNA methylation array, IHC for beta-catenin, FISH for MYC/MYCN amplification

Treatment
Treatment Options for Medulloblastoma
Treatment is risk-stratified based on age, extent of resection, metastatic status, and molecular subgroup.

Surgery

Maximal safe resection via posterior fossa craniotomy. Gross total resection improves outcomes. Careful attention to cerebellar mutism risk.

Craniospinal Irradiation

Standard for children >3 years. Reduced-dose CSI for average-risk WNT/non-metastatic. Boost to tumor bed and metastatic sites.

Chemotherapy

Cisplatin/vincristine/cyclophosphamide-based regimens. Adjuvant after radiation. High-dose chemo with stem cell rescue for infants.

Targeted Therapy

SMO inhibitors (vismodegib, sonidegib) for SHH subgroup. CDK4/6 inhibitors under investigation for Group 3/4.

Infant Protocols

Chemotherapy-only approaches to avoid/delay radiation in children <3 years. Intensive regimens with autologous transplant.

Clinical Trials

Molecular subgroup-directed trials. De-escalation for WNT, intensification for high-risk Group 3.

Find matching trials →
Care Team
Your Multidisciplinary Care Team
Medulloblastoma treatment requires a specialized multidisciplinary team with pediatric neuro-oncology expertise.
Core Specialists

Neurosurgeon

Primary specialist for surgical resection and skull base approaches

Radiation Oncologist

Plans and delivers radiation therapy and stereotactic radiosurgery

Neuro-oncologist

For higher-grade or refractory medulloblastomas requiring systemic therapy

Support Team

Neuroradiologist

Specialized imaging interpretation and monitoring

Neuropathologist

Tissue analysis, WHO grading, and molecular profiling

Nurse Navigator

Guides you through appointments, insurance, and logistics

Resources
Support Organizations
Organizations providing information, community, and support for medulloblastoma patients and families.

CERN Foundation

Collaborative Ependymoma Research Network supporting research for all embryonal tumors including medulloblastoma.

Visit CERN Foundation →

Pediatric Brain Tumor Foundation

Resources, support, and research funding for families affected by childhood brain tumors.

Visit Pediatric Brain Tumor Foundation →

National Brain Tumor Society

Leading nonprofit investing in research, advocacy, and patient services for all brain tumors.

Visit National Brain Tumor Society →

St. Baldrick's Foundation

Funding childhood cancer research including medulloblastoma clinical trials and biology studies.

Visit St. Baldrick's Foundation →