Ichthyosis denotes a group of hereditary skin diseases. The most common forms include ichthyosis vulgaris, transmitted as an autosomal dominant trait, and ichthyosis transmitted as an X-chromosome-linked recessive trait. In this patient, the scaling is light-coloured and powdery, consisting of small scales and concentrating especially on the outer aspects of the extremities. It the symptoms are mild they may be easily masked by atopic eczema. In the X-chromosome-linked form, the scales are more brownish and larger, and the symptoms are concentrated especially on flexural areas, abdomen and legs. See also close-up.