 - Prior Therapy: Patients who underwent surgery for a progressive plexiform neurofibroma will be eligible to enter the study after the surgery, provided the plexiform neurofibroma was incompletely resected and is measurable. Patients are only eligible if complete resection of a plexiform neurofibroma with acceptable morbidity is not feasible, or if a patient with surgical option refuses surgery. Patients may have been previously treated for a plexiform neurofibroma but must have fully recovered from the acute toxic effects of all prior chemotherapy or radiotherapy prior to entering this study. 