A Nonepidermolytic Keratinocytic Epidermal Naevus Associated with a Postzygotic Mutation in the Gene Encoding Epidermal Growth Factor Receptor

Non-epidermolytic keratinocytic epidermal nevi (KEN) are benign congenital skin lesions exhibiting verrucous acanthosis and hyperkeratosis characterized by a linear distribution along the lines of Blaschko. Non-epidermolytic KEN arise as a result of prenatal postzygotic mutations in components of either the rat sarcoma (RAS)/mitogen-activated protein kinase (MAPK) pathway or phosphoinositide-3 kinase (PI3K)/AKT pathway.