Medulloblastoma

Medulloblastoma
CT scan, showing a tumorous mass in the posterior fossa, giving rise to obstructive hydrocephalus, in a six-year-old girl
Classification and external resources
Specialty	Oncology
ICD-O	M9470/3
OMIM	155255
DiseasesDB	31105
eMedicine	neuro/624 ped/1396 radio/434
MeSH	D008527
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Medulloblastoma (/məˌdʌloʊblæˈstoʊmə/) is the most common type of pediatric malignant primary brain tumor (cancer), originating in the part of the brain that is towards the back and the bottom, on the floor of the skull, in the cerebellum or posterior fossa.

The brain is divided into two main parts, the larger cerebrum on top and the smaller cerebellum below towards the back. They are separated by a membrane called the tentorium. Tumors that originate in the cerebellum or the surrounding region below the tentorium are therefore called infratentorial.

Historically medulloblastomas have been classified as a PNET (primitive neuroectodermal tumour), however it is now known that medulloblastoma is distinct from supratentorial PNET's and are no longer considered similar entities.

Medulloblastomas are non-invasive rapidly growing tumors that, unlike most brain tumors, spread through the cerebrospinal fluid (CSF) and frequently metastasize to different locations along the surface of the brain and spinal cord. Metastasis all the way down to the cauda equina at the base of the spinal cord is termed "drop metastasis".

The cumulative relative survival rate for all age groups and histology follow-up was 60%, 52%, and 32% at 5 years, 10 years, and 20 years, respectively, with children doing better than adults.

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