Ichthyosis is a term that describes a group of skin disorders in which the skin becomes extremely dry and scaly, flaky or thickened. This group of skin disorders is so-named because the skin of affected individuals somewhat resembles the scales of a fish; the word itself is derived from ichthys, the ancient Greek word for fish.
The condition is characterized not only by the appearance of the skin, but also by the underlying cause of this symptom. In most forms of ichthyosis, the condition is the result of the fact that the natural shedding of skin cells is greatly slowed down. In some cases, the condition is exacerbated by an increased rate in the production of skin cells.
Almost all forms of ichthyosis are genetic disorders, and only a very small number of cases of severe “acquired” ichthyosis have ever been recorded. Approximately 95% of cases of the condition are of a variety called ichthyosis vulgaris, and this type of ichthyosis has a prevalence of around one in 250.