In addition to the well established epidermal nevus syndromes, such as Schimmelpenning, Becker, Proteus, CHILD, or nevus comedonicus syndromes, the group of less well defined phenotypes associated with epidermal nevi presently includes nevus trichilemmocysticus syndrome, didymosis aplasticosebacea, SCALP syndrome (sebaceous nevus, central nervous system malformations, aplasia cutis congenita, limbal dermoid,and pigmented nevus), Gobello syndrome, Bäfverstedt syndrome, NEVADA syndrome (nevus epidermicus verrucosus with angio-dysplasia and aneurysms), and CLOVE syndrome (congenital lipomatous overgrowth, vascular malformations, and epidermal nevus). These syndromes can thus far be regarded as being in limbo. Future clinical and molecular research may show which of these disorders can be added to the list of well defined nosologic entities.

After completing this learning activity, participants should be able to understand why the list of distinct epidermal nevus syndromes can thus far not be regarded as being complete; why clinicians, when seeing a patient with an epidermal nevus syndrome that is difficult to categorize, should bear in mind the group of less well defined epidermal nevus syndromes; and how practical dermatologists can help recognize rare forms of epidermal nevus syndromes and categorize them appropriately.