Patients who received prior medical treatment for their plexiform neurofibroma(s) must have recovered from the toxic effects of all prior therapy before entering this study. The Cancer Therapy Evaluation Program Common Terminology Criteria for Adverse Events (CTCAE-3) Version 3.0 will be used for toxicity assessment. A copy of the CTCAE version 3.0 can be downloaded from the CTEP home page (http:// ctep.cancer.gov). Recovery is defined as a toxicity grade less than 2, unless otherwise specified in the Inclusion and Exclusion Criteria.