Café-au-lait macules and intertriginous freckling in piebaldism: clinical overlap with neurofibromatosis type 1 and Legius syndrome.

Piebaldism is an autosomal dominant disorder characterized by congenital hypopigmented patches of skin and hair and has been found to be associated with mutations in the KIT or SLUG genes. Café-au-lait macules (CALM) may occasionally be seen in piebaldism. There are four reports describing six patients who were said to have both piebaldism and neurofibromatosis type 1 (NF1) due to the presence of multiple CALM and intertriginous freckling, but none of these patients had undergone comprehensive NF1 mutation analysis. We describe a large family with piebaldism in which two members meet diagnostic criteria for NF1 based on the presence of >5 CALM and intertriginous freckling. Interestingly, only these two family members are of mixed race, which could be of importance. A novel complex mutation in the KIT gene was identified in several family members affected with piebaldism; the proband meeting diagnostic criteria for NF1 also underwent comprehensive NF1 and SPRED1 testing with no mutations detected. These findings suggest that piebaldism may occasionally include CALM and intertriginous freckling, which may create diagnostic confusion especially in the absence of a family history of piebaldism. However, careful clinical evaluation and molecular testing if necessary should distinguish these two disorders.