====== Medulloblastoma, SHH-activated, and TP53-mutant ======

Typical in childhood. Male:female = 1:1. Predominant histologic variant: large cell/anaplastic. The putative cell of origin: cerebellar granule neuron cell precursors of the external granule cell layer and cochlear nucleus; less likely neural stem cells of the subventricular zone. Frequent genetic mutations: [[TP53]].

▶ Classic morphology. Prognosis: high-risk tumor. Uncommon.

▶ Large cell/anaplastic morphology. Prognosis: high-risk tumor. Prevalent in ages 7–17 years. 

▶ Desmoplastic/nodular morphology. Very rare. Uncertain clinical significance.