The Lambert type of ichthyosis hystrix (IHL) is characterized by normal skin at birth that develops striking spiny hyperkeratotic lesions within a few months. There is sparing of the face, palms, and soles, and affected individuals do not experience blistering. Marked improvement of lesions during the summer months has also been observed in some patients. Ultrastructurally, binuclear cells and tonofilament shells surrounding the nucleus in upper keratinocytes are observed (summary by Penrose and Stern, 1958; Wang et al., 2007; Wang et al., 2016). Another form of ichthyosis hystrix, the Curth-Macklin type (IHCM; 146590), includes severe palmoplantar keratoderma among its features and is caused by mutation in the KRT1 (139350) gene. [from OMIM]