Systemic epidermal nevus with involvement of the oral mucosa due to FGFR3 mutation.

Background: Epidermal nevi (EN) represent benign congenital skin lesions following the lines of Blaschko. They result from genetic mosaicism, and activating FGFR3 and PIK3CA mutations have been implicated.

Case Presentation: We report a female patient with a systemic keratinocytic nevus also involving the oral mucosa.