Study of PEG-Intron for Plexiform Neurofibromas

PEG-Intron will be given every week through a small needle under the skin, in the same way that insulin is given to people with diabetes. Subjects will be taught to do this at home. As long as the tumor isn't growing and the side effects are tolerable, the injections will be given once a week for 2 years. Children will be enrolled on the study into one of three strata (patient groups): strata 1 includes children who do not have any symptoms associated with their PNF and MRI scans over the past year may or may not show tumor growth, strata 2 includes children who have symptoms associated with the PNF but MRI scans over the past year have not shown growth and strata 3 includes children who have shown an increase in the size of the PNF on MRI scans over the past year, with or without any symptoms.