What is Under the Tent? Posterior Fossa Tumors in Children, the Usual Suspects—Part 1

Pediatric posterior fossa tumors are a major cause of morbidity and mortality in children. In this 2-part series, we discuss the spectrum of posterior fossa tumors and their clinical and molecular characteristics. In Part 1, the authors discuss the 5 primary differential diagnoses of posterior fossa tumors: medulloblastoma, pilocytic astrocytoma, ependymoma, diffuse midline glioma, H3K27 -altered, and atypical teratoid/rhabdoid tumors. Each posterior fossa tumor is clinically and histologically defined. Additionally, relevant epidemiology data, current genetics/molecular classification according to the fifth edition of the World Health Organization Classification of Tumors of the Central Nervous System, and imaging findings are reviewed. The new version of the international standard for the classification of central nervous system tumors introduces major changes that advance the role of molecular diagnostics in the pediatric central nervous system tumor classification, particularly in posterior fossa tumors, which may impact management and outcomes.Learning Objective: To recognize the imaging appearance of the most common posterior fossa tumors in children.