There are many types of ichthyosis which range from mild types of ichthyosis vulgaris to very rare severe forms such as lamellar ichthyosis. The two most important and common forms of ichthyosis are discussed below.

Ichthyosis vulgaris, an autosomal dominant disease, is the most common hereditary form of ichthyosis. It is characterized by the appearance of dry, rough, whitish scales, which are variable in size, on the extensor surfaces of the arms and legs, and to a lesser extent on the back. The disease usually appears in infancy or early childhood and tends to regress with age. About half the patients also have atopic dermatitis and other signs of atopy. The course of the disease is largely unpredictable, but it is often exacerbated by environmental factors, and particularly by cold.

Acquired ichthyosis is most prevalent in tropical climates, where it is associated with nutritional deficiency disorders, chronic lepromatous leprosy and other debilitating infectious diseases. Clinically, it resembles ichthyosis vulgaris, but it develops later in life as a secondary manifestation of other diseases, including malignant diseases such as lymphoma.

Treatment

Treatment is similar to that of xerosis (see below).