Ichthyosis

The name comes from the Greek “ichthys”, fish, and describes the scaly appearance of the skin. The outermost layer of the epidermis, the horny layer, is made up of dead cells rich in keratin, cemented together by lipids. Together they form the skin barrier, which keeps water inside and blocks the entry of irritants. In the ichthyoses this barrier is defective: either the cells are produced too quickly, or they fail to shed normally at the surface, or the lipids binding them have an abnormal composition. The result is dry skin that scales continuously and loses excess water.

The role of filaggrin. In the most common form, ichthyosis vulgaris, the production of filaggrin is impaired — a protein that helps organise keratin and whose breakdown yields the natural moisturising factors of the skin. Filaggrin deficiency explains the marked dryness, the scaling and the frequent association with atopic dermatitis.

Who is affected. Ichthyosis vulgaris is common and may go undiagnosed, being mistaken for simple dry skin. The other forms are rare and appear at birth or within the first months of life. Most are genetically transmitted — dominantly, recessively or linked to the X chromosome — but acquired ichthyoses also exist, appearing in adults in the context of other diseases or of certain treatments.

The main forms.

• Ichthyosis vulgaris — the most frequent. Fine whitish or greyish scales, mainly on the extensor surfaces of the limbs and on the trunk, with accentuated palmar lines and rough skin on the arms. The flexural folds are usually spared. It improves in summer and worsens in winter.
• X-linked ichthyosis — affects practically only boys, with larger, polygonal, brown scales on the neck, trunk and limbs.
• Lamellar ichthyosis — the newborn may be covered by a translucent membrane that peels off in the first weeks, leaving large brown plates in a mosaic pattern over the whole body surface. Ectropion, deformed ears and impaired sweating are frequent.
• Congenital ichthyosiform erythroderma — red, diffusely inflamed skin covered by fine whitish scales, with variable itching.
• Hyperkeratotic ichthyosis — marked thickening of the horny layer, with warty plaques, especially in the folds and on flexural areas.
• Epidermolytic ichthyosis — at birth skin fragility predominates, with blisters and denuded areas; later a thick brown hyperkeratosis sets in, with a characteristic odour caused by bacterial colonisation.

What the patient notices and how it evolves. The skin is permanently dry and rough, with scaling that returns within a few days of being removed. Painful fissures may develop on the palms, soles and fingertips, along with itching, discomfort in the heat because of reduced sweating and, in severe forms, difficulty moving. The diseases in this group are chronic and stay with the patient for life, with periods of improvement and of worsening. Many forms ease partially at puberty.

What makes it worse. Cold dry winter air, indoor heating, air conditioning, frequent washing with alkaline soaps or very hot water, vigorous rubbing, clothing made of wool or coarse synthetic fibres, and superimposed skin infections. A short lukewarm bath followed immediately by an emollient applied to still-damp skin is the basic measure recommended in daily care.

At our practice, ichthyosis is approached through the Kozak Method — internal and external treatment, individualised, based on consultation. Results differ from one patient to another.