MEDICAL CASE STUDY

Ichthyosis

Artist/ Title/ Date

Tivadar Csontváry Kosztka/Old Fisherman/1902

Description of Disease & Etiology

Ichthyosis is a group of related conditions characterized by scaly, often erythematous skin resulting from disruption of epidermal barrier function. Both inherited and acquired forms of ichthyosis exist. The stratum corneum of the epidermis, composed of corneocytes embedded in a lipid-rich matrix, provides a crucial barrier to transepidermal water loss. In ichthyosis, this layer may show abnormal keratinization and hyperkeratosis (as seen in epidermolytic hyperkeratosis) or abnormal retention of corneocytes (as seen in lamellar ichthyosis). The Greek root ichthy (fish) refers to the scaling appearance seen in many forms of this condition. Dry, cold climates tend to exacerbate symptoms, whereas warm, humid environments appear protective, likely because of improved water retention within the stratum corneum. Depending on the variant, etiologies range from genetic mutations in key epidermal genes to acquired forms associated with malignancy, infection, metabolic disorders, autoimmune disease, or medication use. Readers interested in specific etiologies may consult DiGiovanna and Robinson-Bostom (2003) and Gutiérrez-Cerrajero et al. (2023) for detailed discussion.

Signs/Signifiers of Illness

Patients with ichthyosis commonly experience pruritus, thickened skin with cracking or fissuring, restricted range of motion, and recurrent skin infections. Hypohidrosis (reduced or absent sweating) with heat intolerance is also seen in some individuals. Because ichthyosis encompasses multiple subtypes, clinical signs vary widely. For example, the pattern and texture of hyperkeratosis differs between forms, and features such as migratory erythematous patches, alopecia, and keratosis pilaris may also be present in certain variants.

Pathology

In inherited forms of ichthyosis, genetic testing can be useful in diagnosis. For example, in X-linked ichthyosis, cholesterol sulfate accumulates in the epidermis due to deficiency of the steroid sulfatase enzyme. Diagnostic evaluation often focuses on enzyme activity or its metabolic byproducts. Histopathologic features are also informative. In classic lamellar ichthyosis, biopsies of the palms or soles demonstrate hyperkeratosis with thickening of the stratum corneum. In ichthyosis vulgaris, there is a reduction or absence of the granular cell layer. Clinically, the resulting hyperkeratosis seen in many forms of this disease predisposes some patients to recurrent infections due to fissuring and disruption of the skin barrier.

Treatment

Management of ichthyosis centers on three key strategies: hydration, lubrication, and keratolysis. Humidifiers and frequent bathing increase skin hydration, reflecting the protective effect of humid environments. Mechanical debridement or exfoliation after bathing helps remove thickened scale. Lubrication with oils and emollients helps seal in moisture. Keratolytic agents such as lactic, glycolic, and salicylic acids promote desquamation and reduce scale thickness. Systemic retinoids may benefit certain severe forms, but because ichthyosis is chronic, long-term retinoid use increases the risk of cumulative side effects. Emerging gene-based and molecular therapies are currently under development and may offer future disease-modifying treatment options for specific inherited forms of ichthyosis.

Social Determinants of Illness

Because ichthyosis encompasses a wide spectrum of genetic and acquired disorders, identifying a single, unified set of social determinants is challenging. Acquired forms alone may be associated with malignancy, infection, and nutritional deficiencies, making social risk factors highly variable. In general, timely access to dermatologic care, patient education, and availability of effective treatments are likely to improve outcomes. Socioeconomic status may influence disease severity indirectly by affecting access to moisturizers, medications, and specialist care.

Author(s): Victoria Rhodes

Citations:

Gutiérrez-Cerrajero, C. et al. Ichthyosis. Nat. Rev. Dis. Primer 9, 2 (2023).

DiGiovanna, J. J. & Robinson-Bostom, L. Ichthyosis. Am. J. Clin. Dermatol. 4, 81–95 (2003).

Joosten, M. D. W., Clabbers, J. M. K., Jonca, N., Mazereeuw-Hautier, J. & Gostyński, A. H. New developments in the molecular treatment of ichthyosis: review of the literature. Orphanet J. Rare Dis. 17, 269 (2022).