Ichthyosis hystrix is a rare autosomal dominant skin disorder characterized by spiky, verrucous hyperkeratosis of palms and soles. Diagnosis is supported by specific ultrastructural abnormalities such as perinuclear tonofibril shells of keratin intermediate filaments in binucleated suprabasal keratinocytes. It has been postulated that mutations in KRT1 result in a phenotype with the presence of palmoplantar keratoderma, the Curth-Macklin type (IHCM), while mutations in KRT10 cause the Lambert type (IHL), in which palmoplantar keratoderma is absent.
