Pediatric low-grade gliomas are the most frequent pediatric brain tumors; with countrywide registration in Germany, they constitute 40–50 % of CNS tumors below the age of 18 years. Median age at diagnosis is around 6–8 years, and around 7 % of patients are younger than 1 year. All series confirm a small male preponderance with a sex ratio of 1.1–1.3:1 1) 2).