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The ichthyoses are a rare group of disorders caused by a defect in the synthesis or metabolism of proteins and lipids involved in maintaining the skin epidermal barrier. This results in epidermal thickening, scaling, and cutaneous erythema. Treatment for all forms of ichthyosis is tailored toward management of clinical manifestations by limiting excess transepidermal water loss (TEWL), hydrating and softening the stratum corneum, promoting desquamation of scales, controlling pruritus, and reducing erythema. Frequent bathing, environmental humidification, and use of topical emollients are part of foundational management. Aggressiveness of therapy depends on age morphology, distribution, severity of disease, and whether the disorder is nonsyndromic or involves internal organs as well (syndromic). Studies related to anti-inflammatory biologics, small molecule inhibitors, enzyme replacement medications, and gene therapy are advancing toward clinical trials or already under investigation.
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Levels of evidence are based on the Journal of the American Academy of Dermatology guidelines: Level IA evidence includes evidence from meta-analysis of randomized controlled trials; level IB evidence includes evidence from ≥1 randomized controlled trial; level IIA evidence includes evidence from ≥1 controlled study without randomization; level IIB evidence includes evidence from ≥1 other type of experimental study; level III evidence includes evidence from non-experimental descriptive studies, such as comparative studies, correlation studies, and case control studies; and level IV evidence includes evidence from expert committee reports or opinions or clinical experience of respected authorities, or both. See Table 33-1.
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