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Last Updated: September 28, 2018

Originally named spongioblastoma cerebelli, the term “Medulloblastoma,” or cerebellar primitive neuro-ectodermal tumor, was first described by Cushing and Bailey in their seminal work classifying gliomas in 1924. Further characterization of this lesion occurred in 1983 when all malignant small cell tumors were classified as primitive neuroectodermal tumors (PNETs). The World Health Organization (WHO) continues to designate medulloblastoma as its own distinct entity, universally WHO grade IV.


Medulloblastomas are the most common primary malignant brain tumor in the pediatric population, representing 20-40% of all pediatric brain tumors. They are uncommon in adults, most frequently observed in the third and fourth decade of life. The epidemiology of medulloblastoma varies dependent on subtype, with a peak incidence in infants and young children, followed by another peak in adults older than 16 years of age. This bimodal age distribution distinguishes the medulloblastoma subtype observed in infants/children from that of adults.

Although medulloblastoma is primarily a sporadic lesion, se...