Nagashima-type palmoplantar keratoderma is an autosomal recessive nonsyndromic diffuse palmoplantar keratosis, first described by Nagashima (1977) in the Japanese literature. It is characterized by well-demarcated diffuse erythematous hyperkeratosis that extends onto the dorsal surfaces of the palms and feet and the Achilles tendon area. Involvement of the elbows and knees has also been reported, and there is a high frequency of hyperhidrosis on the palms and soles. In contrast to other types of transgressive diffuse hyperkeratosis such as mal de Meleda (248300), PPKN shows only mild hyperkeratosis that is nonprogressive after the second decade and does not involve flexion contractures or constricting bands (summary by Kubo et al., 2013). For a discussion of phenotypic and genetic heterogeneity of palmoplantar keratoderma, see epidermolytic PPK (144200).