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noun, plural: ichthyoses

A skin disorder characterized by having thick, scaly skin due to excessive skin keratinization or cornification


Ichthyosis is a skin disorder characterized by having a dry, thick, scaly skin. Its name is derived from the Greek ichthys meaning fish. The skin is compared to the scaly outer covering of the fish. The scaly appearance of the skin is due to excessive skin keratinization or cornification.

Ichthyosis may be classified based on the underlying cause. Genetic ichthyosis is a type of ichthyosis caused by a defective gene. Most cases of ichthyoses are genetic. Some of these are ichthyosis vulgaris, X-linked ichthyosis, epidermolytic hyperkeratosis, harlequin-type ichthyosis, ichthyosis bullosa of Siemens, ichthyosis hystrix (Curth-Macklin type), CHILD Syndrome, Conradi-Hünermann syndrome, ichthyosis follicularis with alopecia and photophobia syndrome, keratitis-ichthyosis-deafness syndrome, Netherton syndrome, and neutral lipid storage disease with ichthyosis. When the disorder is genetic, it may be inherited. The parents may pass it on to the child. There are instances when both parents do not exhibit this disorder but are carriers of the mutated gene. When a child inherits the mutated gene from both parents, the child will exhibit ichthyosis.

Ichthyosis acquisita is a non-genetic type of ichthyosis. It is not congenital but acquired in adulthood. It is associated with other medical conditions such as leprosy, typhoid fever, HIV, autoimmune conditions, malignancies (e.g. Kaposi's sarcoma, visceral carcinoma, etc.), endocrine diseases, and metabolic diseases.


  • xeroderma
  • fishskin disease

See also:

Related form(s):

  • ichthyotic (adjective, of or pertaining to ichthyosis)