Neurofibromatosis (NF) has perhaps been the most notorious of the neurocutaneous disorders. Both Quasimoto of Victor Hugo's The Hunchback of Notre Dame and John Merrick, known as the Elephant Man (who subsequently has been more properly classified as having Proteus syndrome, a quite different disorder), are 2 infamous examples that have shaped many popular misconceptions about this disease. Neurofibromatosis is now understood as a hamartomatous disorder on the basis of molecular genetic studies. Studies on NF have been pivotal to understanding the functions of oncogenes in tumorigenesis.