With a prevalence of 1 in 3-5000 births, neurofibromatosis Type I is one of the most common genetic defects. The mode of inheritance is autosomal dominant and affects a gene (NF1), which is responsible for the production of the tumor suppressor protein neurofibromin. The consequence is an uninhibited expansion of neural tissue which leads amongst others to cosmetic disfigurement of the patients. In comparison to the plexiform neurofibromas the cutaneous tumors do not undergo malignant transformation.