Summary

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.

Ichthyosis vulgaris

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]

X-linked ichthyosis

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]