Ichthyosis is a skin disease with more than 20 varieties. Ichthyosis vulgaris is the most common and mildest form of ichthyosis. Of those who have some form of ichthyosis, 95% have ichthyosis vulgaris. The main feature of ichthyosis vulgaris is dry, thick and scaly skin. The condition can begin in childhood, often in the first year of life. Adults can also develop the disease. Ichthyosis vulgaris is fairly common, affecting one of every 250-300 people (male and female, and of all races).