History:

 Epidermal nevus (Verrucous nevus or Nevus verrucosus) is a focal area of abnormal epidermal development following Blaschko lines and having a variety of histologic patterns, sometimes associated with systemic abnormalities (epidermal nevus syndrome). An epidermal nevus is always present at birth, but sometimes not recognized as it may be flat, perhaps slightly pigmented, and only later become hyperkeratotic. It may range in color from pale tan to dark brown. Most typical locations are face, neck, upper trunk. The presented case is typical of epidermal verrucous nevus following Blaschko lines confined to one side (unilateral) of the trunk and upper limb.