Palmoplantar epidermal differentiation disorders: a new classification toward pathogenesis-based therapy

More than 50 palmoplantar epidermal differentiation disorders (pEDDs) have been reported in the literature. Various descriptors have been used to name these conditions, including clinical features often designated as acronyms or evocative terms, and names of clinicians and of geographical locations. Not only has this nomenclature been criticized for its lack of methodological consistency, but it has also progressively lost its clinical relevance. Indeed, the advent of a wide range of pathogenesis-targeting therapeutic solutions for these disorders has raised the need for a novel classification of pEDDs, based on their causative genetic defects, to provide clinicians with genuine therapeutic guidance. Here, we present a novel classification scheme for pEDDs and its application in the form of a practical algorithm for the rapid diagnosis of pEDDs.