Porokeratosis—A Mutant Clonal Keratosis of the Epidermis

Porokeratosis (Mibelli's disease) is a heritable disorder of the skin characterized by localized areas of faulty keratinization, resulting in the cornoid lamella, the morphologic and histologic hall-mark of the disease process. In our review of 35 cases there was little evidence to support the belief that the disease had its origin in the ostia of sweat ducts. Instead the histogenesis of porokeratosis is best explained as a clonal disease of the epidermis much like actinic keratosis. The tendency of these clones to develop is probably inherited. In many cases the latent abnormal clones become clinically overt following actinic exposure.