Medulloblastoma is an embryonal tumor of the cerebellum. According to the WHO classification of tumors of the central nervous system, it is classified as Grade IV.
Epidemiology
It occurs predominantly in infants and children and is the most common malignant brain tumor in this age group1.
Extracranial Metastases
In up to 50% of cases, medulloblastomas may give rise to extracranial spinal drop metastases2. These typically appear as a "sugar coating" on the dura and nerve roots.
Pathology
There are currently four relevant molecular-pathological subtypes of medulloblastoma which, in combination with the histopathological subtypes, have therapeutic and prognostic relevance3:
- WNT-activated subtype
- Sonic Hedgehog (SHH)-activated subtype
- Group 3 & 4
Location
Medulloblastomas frequently arise from the roof of the fourth ventricle4. Depending on the molecular genetic subtype, there are different patterns of localization5:
| Molecular genetic subtype | Preferred location |
|---|---|
| WNT-activated subtype | Preferentially the cerebellar peduncle / cistern at the cerebellopontine angle |
| SHH-activated subtype | Preferentially in the cerebellar hemisphere |
| Group 3 & 4 | Preferentially in the fourth ventricle |
Imaging
Associated Genetic Syndromes
The occurrence of medulloblastomas is associated with the following genetic syndromes6:
- Gorlin syndrome
- Turcot syndrome
- Li-Fraumeni syndrome
- Rubinstein-Taybi syndrome
References
Warmuth-Metz, M., et al. "Differential Diagnosis of Infratentorial Brain Tumors in Children." Der Radiologe 43.11 (2003): 977-985. ↩ ↩
Rochkind, Semion, et al. "Extracranial metastases of medulloblastoma in adults: literature review." Journal of Neurology, Neurosurgery & Psychiatry 54.1 (1991): 80-86. ↩ ↩
Neurosurgery Case Review: Questions and Answers. Remi Nader, Abdulrahman J Sabbagh. 2020 Thieme Verlage. ISBN 9781626231986 ↩ ↩ ↩ ↩
Differential Diagnosis. In: Greenberg M, ed. Handbook of Neurosurgery. 9th Edition. Thieme; 2019. ↩ ↩
Perreault, S., et al. "MRI surrogates for molecular subgroups of medulloblastoma." American Journal of Neuroradiology 35.7 (2014): 1263-1269. ↩ ↩