Epidermal nevus.

A healthy 25-year-old man presented with a widespread, non-organoid, non-epidermolytic epidermal nevus. In addition to extensive hyperpigented patches and thin plaques following Blaschko lines, there were superimposed psoriasiform plaques on the elbows and warty plaques on the upper trunk. Striate palmar keraoderma also was evident. We review the clinical morphologies, sites of involvement, histopathologic findings (presence or absence of epidermolytic hyperkeratosis), and syndromal associations of non-organoid EN with underlying mutations in different genes.