Section 15: Ichthyoses and Disorders of Keratinization

Ichthyosis vulgaris This is the mildest and most common form of ichthyosis, with an incidence in school-aged children as high as 1:250. It is inherited as an autosomal dominant trait and is present in a significant percentage of individuals with atopic dermatitis. It is not present at birth.

The clinical appearance of this ichthyosis varies, depending on location. Figures 15-1 and 15-2 illustrate the fine, bran-like scaling on the upper chest and back. Children with ichthyosis vulgaris are likely to have increased skin markings on the palms and soles and a high incidence of keratosis pilaris (see Figs. 15-61,15-62,15-63,15-64).

Ichthyosis vulgaris On the anterior lower leg, there are often larger, plate-like scales that resemble the skin of a fish (Figs. 15-3 and 15-4). Facial involvement is usually minimal, and flexural areas are typically spared.

Ichthyosis vulgaris tends to worsen in winter when there is less sweating and lower humidity. Treatment of ichthyosis vulgaris entails the use of emollients and creams and ointments containing urea, lactic acid, and other alpha-hydroxy acids. Excessive bathing and the use of alkaline soaps should be avoided. The exacerbation that frequently occurs in winter months can be lessened if a humidifier is used in the child’s room.

Harlequin–type ichthyosis The newborn infant is covered with thick plates of scale that are often described as resembling a coat of armor. After birth, deep erythematous fissures form between areas of scale. There is also severe facial disfigurement due to eclabium, ectropion, and edema of the conjunctiva. The texture of the skin results in restriction of the respiratory movements of the chest and interferes with normal feeding. This form of ichthyosis is due to a mutation on the ABCA12 gene.

Collodion baby This is a descriptive term for the child who is born encased in a taut, parchment-like membrane, accompanied by ectropion and eclabium. The outcome of this process is unpredictable. When the membrane is completely shed, the infant may go on to develop one of several ichthyosis skin types. Lamellar ichthyosis and congenital ichthyosiform erythroderma (pictured in Fig. 15-6) are the most common. A small percentage of infants go on to have completely normal skin, a phenomenon called “self-healing collodion baby.”

Collodion baby Collodion babies are at risk for complications. These include infection, ...