1. Progressive, debilitating, severely disfiguring or life-threatening plexiform neurofibroma (PN) which is not surgically resectable and for which there is no other standard medical management. Histologic confirmation of tumor is not required in the presence of consistent clinical and radiographic findings. However, if any clinical observation or scan suggests possible malignant transformation, the tumor must be biopsied prior to therapy. In addition to PN, all study subjects must have at least one other diagnostic criteria for Neurofibromatosis type 1 (NF1) listed below: