Neurofibromatosis is a complex neurocutaneous syndrome inherited as an autosoma1 dominant trait with high penetrance of the mutated gene (for reviews, see References 1-3). Approximately half of the cases with neurofibromatosis appear to represent new mutations, and the mutation frequency of the affected gene has been estimated to be as high 4.3 Y 10-5.4* 5 The overall frequency of neurofibromatosis in the general population has been estimated to be 20-40 per lOO, OOO.".'Thus, neurofibromatosis is probably the most common neurocutaneous single-gene disorder. The diagnosis of neurofibromatosis is based on clinical findings, positive family history, and associated features. The cutaneous lesions of neurofibromatosis include neurofibromas, dermal or subcutaneous tumors of varying sizes, and cafk-au-lait spots, pigmented cutaneous macules of varying sizes and The diagnosis of neurofibromatosis can be based on the following criteria:'s4s9