1. Affiliations of authors: Rare Tumor Initiative (KMR), Laboratory of Pathology (MMM), and Pediatric Oncology Branch (BCW), Center for Cancer Research, National Cancer Institute, Bethesda, MD; Center for Cancer and Blood Disorders, Children’s National Medical Center, Washington, DC (AK); Department of Neurology, Johns Hopkins Hospital, Baltimore, MD (JB); Neurofibromatosis Center, Department of Neurology Guy's Hospital Lo