Ichthyosis is a broad term used to describe a family of rare, genetic skin diseases. The main characteristics of the diseases are dry, thickened and scaly skin, states WebMD.
Ichthyosis usually starts in infancy or childhood. It can be inherited, or it can develop later in life. In the majority of cases, its cause is linked to one or more genetic mutations, notes Drugs.com.
The healthy human body continuously renews its skin surface by building new skin cells, allowing the older skin cells to fall off. This balance is disrupted with ichthyosis, as either too many replacement cells are formed, or the older skin cells do not separate properly from the surface of the skin when it is their time to fall off. This results in an accumulation of skin cells that develop into thick flakes and stick to the body. The thick flakes resemble fish scales, states Drugs.com.
The most common form of ichthyosis is ichthyosis vulgaris. It is the mildest form of the disease and occurs in one out of every 250 people. Symptoms of ichthyosis vulgaris include itchy skin, a flaky scalp, severely dry skin and scales on the skin that are brown, gray or white, notes Healthline.