The hereditary palmoplantar keratoses: an updated review and classification.

The palmoplantar keratoses (PPKs) comprise a heterogeneous group of disorders of keratinization, which can be subdivided into hereditary and acquired forms. Many authors have attempted to classify the hereditary forms, and most classifications have been based on the morphology, distribution, associated symptoms and mode of inheritance. Subsequently, many new forms have been recognized, and what were previously considered to be distinct types have been shown to be variants of a single type, both of which limit the usefulness of previous classifications. Hence, we propose a new, updated classification, which enables accurate diagnosis of these disorders.