Circumscribed palmoplantar hypokeratosis

Circumscribed palmoplantar hypokeratosis (CPH) is a rare acquired dermatosis first described in 2002. It affects mostly the thenar or hypothenar eminences of the palm of middle-aged or elderly women and manifests clinically with sharply limited, annular erythematous plaques with a depressed surface, rimmed by a slightly raised, keratotic border. Microscopically, circumscribed palmoplantar hypokeratosis shows a sharp decrease of the horny layer thickness, with few, if any, associated changes (parakeratosis, dermal inflammation). Despite a characteristic clinical and microscopic aspect, the disease remains poorly known, as does its pathogenesis, even if several hypotheses have been proposed (clonal epidermal malformation, disorder of epidermal differentiation/keratinization and/or desquamation, human papillomavirus- or trauma-induced disease). Several therapies have been proposed with varying results, the best ones achieved with surgical excision; however, because the disease is benign, intervention is optional. © 2020 Elsevier Inc. All rights reserved.