title: Pilocytic astrocytomas.
abstract: Pilocytic astrocytoma (PA) is the most common pediatric brain tumor in children. PAs are a distinct histologic and biologic subset of glioma that have a slow growth rate and may even spontaneously regress. These tumors tend to arise in the cerebellum and chiasmatic/hypothalamic region, but can also occur in other regions of the central nervous system. Dissemination is uncommon, but may occur in newly diagnosed PAs. Alterations in the Ras/RAF/mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) pathway (Ras/ERK) have been discovered in a majority of PAs, with KIAA1549-BRAF fusions being the most commonly identified alteration. Children with neurofibromatosis 1 are predisposed to developing PAs, primarily within the optic pathway. When required, treatment consists of surgery, chemotherapy, and/or radiation, although new molecular agents targeting the Ras/ERK and related signaling pathways are promising new approaches. The 10-year survival rates are greater than 90% in pediatric patients; however, they are poorer in adults. Tumors that are amenable to complete resection (i.e., cerebellum and cortex) have the best overall survival.
authors.affiliation: Gilbert Family Neurofibromatosis Institute and Brain Tumor Institute, Children's National Health System, Washington, DC, USA.
authors.forename: Miriam
authors.initials: M
authors.lastname: Bornhorst
authors.affiliation: Department of Pediatric and Adult Neuro-oncology, Centre Léon Bérard and Institute of Pediatric Hematology and Oncology, Lyon, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Frappaz
authors.affiliation: Gilbert Family Neurofibromatosis Institute and Brain Tumor Institute, Children's National Health System, Washington, DC, USA. Electronic address: RPacker@childrensnational.org.
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Packer
mesh_terms: D001254:Astrocytoma / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D002648:Child; D006801:Humans
keywords: BRAF; NF1; glioma; low grade; pilocytic astrocytoma; tumor