Medulloblastoma

Excerpt

Medulloblastoma represents the most common malignant brain tumor in children, accounting for approximately 25% of all pediatric central nervous system (CNS) tumors. Classified as a World Health Organization (WHO) grade 4 embryonal tumor, medulloblastoma arises primarily in the posterior fossa, most often from the cerebellum. Pediatric populations account for the majority of cases, with 70% diagnosed in children younger than 10 years. Although rare in adults, medulloblastoma constitutes less than 1% of adult CNS tumors. Annual incidence in children younger than 19 years old is 0.39 per 100,000, peaking between ages 3 and 7. Despite advances in multimodal therapy, including surgical resection, craniospinal irradiation, and chemotherapy, medulloblastoma remains a leading cause of cancer-related morbidity and mortality in children. Overall, 5-year survival ranges from 65% to 70%, with survivors frequently experiencing long-term neurocognitive and neuroendocrine complications.

The 2021 World Health Organization (WHO) Classification categorizes medulloblastoma by molecular subgroup: WNT-activated, SHH-activated/TP53-wildtype, SHH-activated/TP53-mutant, and non-WNT/non-SHH (encompassing groups 3 and 4), incorporating integrated molecular-histologic diagnostics. Each subgroup carries distinct histologic, genetic, clinical, and prognostic features.