Ichthyosis is a disorder of keratinization.
The Ichthyoses are a family of skin diseases with the shared characteristic that each causes the skin to build up and scale. The degree of scaling can vary, from mild dry skin to severe heavy scaling. Ichthyosis scaling can be very painful, can restrict the body's range of movement, cause deep cracks or fissures at the joints, and affect hearing. Some say it can be inherited or acquired. In a typical case, the skin is dry and rough, with small grayish brown scales, usually found on the exterior surfaces of the limbs.