Medulloblastoma
Medulloblastoma is the most common malignant brain tumor in children. It arises in the cerebellum, is classified as grade 4 in the World Health Organization (WHO) classification, and can spread via the cerebrospinal fluid. It requires multidisciplinary treatment combining surgery, radiotherapy and chemotherapy.
Laatst bijgewerkt: 2026-06-06
Definition
Medulloblastoma is a high-grade (WHO grade 4) tumor of embryonal origin arising in the cerebellum. It tends to grow rapidly and can spread along the brain and spinal cord via the cerebrospinal fluid (drop metastasis). It is a major entity among childhood brain tumors.
Epidemiology
Medulloblastoma occurs most often in children aged 3-8 years, although a proportion of cases also arise in adulthood. It is more common in boys than girls and accounts for roughly 15-20% of childhood brain tumors. The tumor is usually located in the midline (vermis); a lateral hemispheric location is more common in adults.
Symptoms
The most common symptoms result from raised intracranial pressure: morning headache, projectile vomiting without nausea, drowsiness, and irritability in infants. Cerebellar involvement may cause unsteady gait (ataxia), incoordination, eye-movement oscillation (nystagmus) and speech disturbance. If there is spinal spread, back pain and leg weakness may appear.
Diagnosis
Contrast-enhanced brain MRI is the gold standard; the tumor typically appears as a strongly enhancing mass at the floor of the fourth ventricle and vermis, accompanied by hydrocephalus in most cases. To assess spread, whole-spine MRI and cerebrospinal fluid cytology are mandatory. Definitive diagnosis is made by pathological examination. The 2021 WHO classification has made molecular subgroup assignment (including DNA methylation profiling) standard.
Molecular Subtypes (2021 WHO CNS5)
Under the 2021 WHO classification, medulloblastoma is divided into four main molecular subgroups: WNT-activated, SHH-activated (further subclassified by TP53 status), group 3 and group 4. These subgroups differ in age distribution, tendency to spread and prognosis; for example, the WNT-activated group is usually very favorable, while group 3 (especially with MYC amplification) is more aggressive. Molecular subgroup assignment is critical for determining treatment intensity and avoiding unnecessary treatment toxicity.
Treatment Options
Treatment is delivered by neurosurgery, radiation oncology and pediatric oncology working together. The first step is the widest safe resection from the cerebellum (suboccipital craniotomy); the extent of resection affects prognosis. After surgery, craniospinal radiotherapy is given according to age and risk group; in very young children, radiotherapy is delayed or its dose reduced. Multi-agent chemotherapy is part of standard treatment; in high-risk cases, intensified protocols and, in selected cases, stem cell transplantation are considered. In the SHH subgroup, targeted agents are under investigation for certain cases.
Prognosis
Prognosis varies markedly with molecular subgroup, risk classification (standard or high risk), age, extent of resection and spread status. With modern multidisciplinary treatment and molecular risk adaptation, good outcomes can be achieved in many children; nevertheless, prognosis is more limited in some high-risk subgroups. The long-term neurocognitive and endocrine effects of treatment must be monitored closely. Outcomes vary individually and no outcome can be guaranteed.
Bronnen
- Greenberg MS. Greenberg's Handbook of Neurosurgery. 10th ed. Thieme; 2023:744-757.
- Winn HR, ed. Youmans Neurological Surgery. 6th ed. Saunders; 2011:1375-1380.
- Osborn AG, Hedlund GL, Salzman KL. Osborn's Brain: Imaging, Pathology, and Anatomy. 2nd ed. Elsevier; 2018:638-642.
- Louis DN, et al. The 2021 WHO Classification of Tumors of the Central Nervous System. Neuro Oncol. 2021.
Dit artikel dient als algemene informatie en vervangt geen medisch onderzoek. Beslissingen over diagnose en behandeling zijn individueel.