Primary Pediatric Brain Tumors of the Posterior Fossa Part II: A Comprehensive Overview of Medulloblastoma

Abstract

Medulloblastoma (MB) is the most common malignant primary brain tumor in children and is currently classified into five distinct molecular subtypes (WNT, SHH-TP53 wild type, SHH-TP53 mutant, Group 3, and Group 4), based on genomic alterations, gene expression profiles, responses to treatment, and developmental cell of origin. The standard treatment for MB consists of surgical resection followed by radiation therapy and chemotherapy. However, current treatments do not take into account the extensive heterogeneity between and within MB subtypes. Cancer stem cells also play an important role in treatment failure and recurrence in MB, adding an additional layer of complexity in the form of cellular heterogeneity. This chapter will focus on the clinical presentation of MB, current treatment options, and histological classifications with a more detailed description of the current molecular subtypes, followed by exploration of cellular heterogeneity in the molecular era. Further dissection of tumor heterogeneity and identification of subtype-specific biomarkers will be crucial in the development of novel diagnostic markers and targeted therapies for these highly aggressive pediatric brain tumors.