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Background: Posterior fossa tumors account for approximately half of the central nervous system tumors in children. Major technological advances, mainly in the fields of molecular biology and neuroimaging, have modified their classification, leading to a more detailed description of these entities. Into the classic taxonomy, used for many years, new concepts have been incorporated at times eliminating or modifying former ones. Methods: A literature search was conducted in PubMed using the medical subject headings involving the five most common pediatric posterior fossa tumors: diffuse midline glioma, medulloblastoma, ependymoma, atypical teratoid/rhabdoid tumor, and pilocytic astrocytoma. Only English published articles in the past 11 years that provided technological, neuroimaging, and molecular biology insight into posterior fossa tumors in children were considered. Results: Substantial changes have been introduced in the nomenclature of pediatric posterior fossa tumors. Diffuse midline gliomas are named based on alterations in histone H3. Molecular rearrangements of medulloblastomas are more important in defining the prognosis than histological variants; therefore, these tumors are currently named based on their molecular subgroups. Posterior fossa ependymomas and atypical teratoid rhabdoid tumor classification have incorporated new groups based on different genetic profiles. Pilocytic astrocytoma has been placed in a new category that distinguishes circumscribed from diffuse entities. Conclusion: Advances in molecular biology and neuroimaging have substantially changed the way pediatric neoplasms are studied. The classical taxonomy has been modified leading to more accurate classifications that are based on the genetic alterations.

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Introduction. High-flow vascular malformations of the brain are uncommon in pediatrics. The objective of this study is to establish the differences among these pathologies and group them by age at onset, clinical manifestations, and angioarchitecture. Population and method. This was a retrospective and observational study. The medical records, imaging studies, and procedure protocols of patients seen at Hospital J. P. Garrahan diagnosed with vascular malformations of the brain between January 2010 and January 2020 were analyzed. Results. A total of 183 patients met the inclusion criteria. It was possible to identify 131 patients with arteriovenous malformations with a nidus (AVMs) and 52 with direct fistulas (without a nidus), including 19 vein of Galen aneurysmal malformations, 23 pial fistulas, and 10 dural fistulas. The average age of patients was 105 months for AVMs, 1.7 months for vein of Galen aneurysmal malformations, 60.5 months for pial fistulas, and 41 months for dural fistulas. Conclusion.Based on their angioarchitecture, high-flow vascular malformations of the brain presented a nidus (AVMs) or direct fistulas (vein of Galen aneurysmal malformations, pial fistulas, and dural fistulas). AVMs were observed in early childhood, especially due to intracranial hemorrhage. Direct fistulas occurred in the first stage of life, commonly with heart failure.