An autosomal dominant disorder characterized by a widely distributed, well-demarcated hyperkeratosis of the palms and soles. There is more than one genotypically distinct form, each of which is clinically similar but histologically distinguishable. Diffuse palmoplantar keratoderma is distinct from palmoplantar keratoderma (KERATODERMA, PALMOPLANTAR), as the former exhibits autosomal dominant inheritance and hyperhidrosis is frequently present.