A patient with NF1 was treated with oral ketotifen for 30 years since infancy. Review of the patient's course and treatment details establishes a basis for reconsideration of several fundamental precepts about NF1 pathogenesis. The data suggest a distinctive benefit to treating an NF1 patient with an inhibitor of mast cell degranulation before cutaneous neurofibromas are clinically apparent: the neurofibromas appear to be arrested at a very early stage of development. The patient's skin was especially remarkable for both the paucity of cutaneous neurofibromas and the distinctive monotonous uniformity of those present, which were small and flat or barely sessile. While the data do not, of themselves, prove that ketotifen treatment commencing in childhood preempts neurofibroma maturation, in the context of earlier publications, they certainly warrant further investigation. © 2015 Wiley Periodicals, Inc.