hyperkeratosis

Thickening of the horny layer of the epidermis or mucous membrane. SEE ALSO: keratoderma, keratosis. SYN: hyperkeratinization.

- h. congenita SYN: ichthyosis vulgaris.

- diffuse h. of palms and soles an autosomal dominant disorder with onset in early infancy; characterized by hyperkeratotic, scaling plaques and often hyperhidrosis on the palms and soles. SYN: Unna-Thost syndrome.

- epidermolytic h. [MIM*144200] characterized by localized lesions, keratosis palmaris and plantaris, and elevated IgE, associated with h., hypergranulosis, and reticular degeneration in the upper epidermis; autosomal dominant inheritance, caused by mutation in the epidermolytic palmoplantar keratoderma gene (EPPK) on chromosome 17q. Generalized epidermolytic h. is present in bullous congenital ichthyosiform erythroderma. SYN: porcupine skin.

- h. follicularis et parafollicularis discrete and confluent horny follicular plugs on a crateriform base, often occurring on the arms and legs in diabetics with renal failure; possibly a severe form of perforating folliculitis. SEE ALSO: perforating folliculitis. SYN: Kyrle disease.

- generalized epidermolytic h. SYN: bullous congenital ichthyosiform erythroderma.

- h. lenticularis perstans [MIM*144150] small hyperkeratotic papules on the dorsa of the feet and legs and occasionally elsewhere, with pinpoint keratotic papules of the palms and soles; onset in the third and fourth decades; an autosomal dominant trait. SYN: Flegel disease.

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hy·per·ke·ra·to·sis -.ker-ə-'tō-səs n, pl -to·ses -'tō-.sēz

1) hypertrophy of the stratum corneum layer of the skin

2 a) any of various conditions marked by hyperkeratosis

b) a disease of cattle that is marked by thickening and wrinkling of the hide, by formation of papillary outgrowths on the buccal mucous membranes, and often by a watery discharge from eyes and nose, diarrhea, loss of weight, and abortion of pregnant animals and that is caused esp. by ingestion of the chlorinated naphthalene of various lubricating oils, by arsenic poisoning, or by inherited congenital ichthyosis called also X-disease, XX disease

hy·per·ker·a·tot·ic -'tät-ik adj

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n.

thickening of the outer horny layer of the skin. It may occur as an inherited disorder, affecting the palms and soles.

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hy·per·ker·a·to·sis (hi″pər-ker″ə-toґsis) [hyper- + keratosis] 1. hypertrophy of the stratum corneum of the skin; see also callus and keratosis. 2. a skin disease of cattle marked by inflammation and thickening of the stratum corneum, and caused by the ingestion of feed containing chlorinated naphthalenes. It was once thought to be caused by a virus and was called x disease.