Ichthyosis

Ichthyoses are a heterogeneous group of dermatoses characterized by dry and scaly skin due to impaired keratinization. They are associated with various diseases, but may also be idiopathic. Ichthyosis vulgaris is the most common type, followed by X-linked ichthyosis. Treatment for both of these conditions mainly consists of skin moisturizers and possibly topical retinoids.

• Epidemiology: most common type of hereditary ichthyosis
• Etiology: autosomal dominant inheritance; associated with atopic diseases
• Clinical presentation
  • Onset usually between 3 and 12 months of age
  • Lesions
    • Generalized fine, white scaling
    • Dry and coarse skin (xerosis): more common on extensor surfaces (skin folds are usually not affected)
    • Hyperlinearity of palms and soles (accentuated skin lines)
    • Symptoms generally worsen in winter and improve in summer
• Diagnosis: clinical
• Treatment: skin moisturizers; (e.g., creams containing urea or panthenol), topical retinoids
• Prognosis: : good prognosis; lesions usually disappear during adolescence

References:^[1][2][3]

• Epidemiology: 1 in about every 6000 male births
• Etiology: X-linked recessive trait (transmitted only to males) → inherited deficiency of the enzyme called steroid sulfatase
• Clinical presentation
  • Generalized scaling, more prominent on extensor surfaces
  • Affected children are usually born via cesarian section (due to prolonged labor in pregnant mothers)
• Diagnosis
  • History and clinical features
  • Biochemical analysis of the placenta, skin fibroblasts, and keratinocytes
  • Genetic analysis
  • Prenatal diagnostic tests
• Treatment
  • No causal treatment available
  • General approach: reduce scaling
    • Topical keratolytics
    • Emollients
    • Hydrating agents
    • Topical retinoids are beneficial in some cases
• Prognosis
  • Mild chronic condition that does not improve with age (unlike ichthyosis vulgaris)
  • Responds well to symptomatic treatment

References:^[1][2][4][5]

1. James WD, Berger T, Elston D. Andrews' Diseases of the Skin: Clinical Dermatology. Elsevier Health Sciences ; 2015
2. Choate K. Overview and Classification of the Inherited iIchthyoses. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. http://www.uptodate.com/contents/overview-and-classification-of-the-inherited-ichthyoses.Last updated: December 6, 2016. Accessed: May 16, 2017.
3. Recessive X-Linked Ichthyosis. http://www.dermnetnz.org/topics/recessive-x-linked-ichthyosis/. Updated: September 1, 2015. Accessed: May 16, 2017.
4. Janniger CK. X-Linked Ichthyosis. In: Elston DM, X-Linked Ichthyosis. New York, NY: WebMD. http://emedicine.medscape.com/article/1111398. Updated: June 22, 2016. Accessed: May 16, 2017.
5. Ichthyosis Vulgaris. http://www.dermnetnz.org/topics/ichthyosis-vulgaris/. Updated: January 1, 2014. Accessed: May 16, 2017.