Heterogeneous non-inflammatory group of disorders characterised by variably sized dry, scaling patches of skin.
Also called xeroderma, hyperkeratosis cognita, ichthyosis simplex. Affects up to 1% of population. Normal rate of keratinisation, but increased adhesiveness of cells in stratum corneum. Autosomal dominant – usually onset between ages 1 to 4 – sometimes up to puberty – usually improves with age. Defect is deficiency in flaggrin. Half have atopy or family history of atopy. Small, fine white scales (‘fish scales’). Get greater creasing of palms and soles with painful fissures – may have moderate hyperkeratosis. Distribution of lesions is generalised but greater in areas of extension. Generally worse in winter (less sebaceous gland activity) and improvement in summer. Treatment is with hydration and emollients.
Also called ichthyosis serpintine, ichthyosis sauroderma and ichthyosis vulgaris. Occurs mainly in males – mild form in female carriers. Appears shortly after birth. Absence of steroid sulfatase activity in the skin results in persistent skin adhesion – also have an increased synthesis of normal keratinocytes. Appear as large ‘dirty’ brown scales. Mostly affects areas of extension. Does not effect palms or soles. Pruritus is present which gets worse with age. Hypogondism and corneal opacities are often associated with it. Treatment – skin hydration.
Lamellar ichthyosis (nonbullous congenital ichthyosiform erythroderma):
Autosomal recessive. More severe form. Born with membrane covering (collodion baby) shed after birth generalised erythroderma develop large yellow or yellow/brown scales that are loose at margins on flexor surfaces periodically shed. Palms and soles may be hyperkeratotic. Usually increased in severity with age. Treatment – skin hydration.
• epidemolytic hyperkeratosis
• congenital ichthyosiform erythroderma
• Harlequin foetus