Epidermolytic Hyperkeratosis is a genetic disorder of keratinization, initially described as bullous ichthyotic erythroderma. It is transmitted as an autosomal dominant trait, although 50% of cases may occur as spontaneous mutations. This disease frequently presents with blistering, redness and peeling at birth. With time it may develop into generalized hyperkeratosis with or without erythroderma. It has a distinctive histopathologic feature of vacuolar degeneration of the upper epidermis and associated thick stratum corneum. Sporadic epidermolytic hyperkeratosis due to postzygotic, spontaneous mutation during embryogenesis may appear in a mosaic pattern of skin involvement showing areas of hyperkeratosis distributed in streaks along Blaschko's lines, and alternating with normal skin. Mutations occur in either keratin 1 and 10. The authors present the case of a 15 year-old adolescent, who since the age of ten has presented vesico-bullous lesions that gradually became hyperkeratotic. They affected the limbs, the body and the cervical region following Blaschko's lines, and alternating with normal skin. The histopathologic study was compatible with epidermolytic hyperkeratosis. He was treated with acitretin, which obtained a good response.
hyperkeratosis; epidermolytic; mosaicism
