What is ichthyosis?
Ichthyosis is the general term of a family of rare genetic skin diseases that are characterized by scaly, thick, and dry skin. There are many different types of ichthyosis, distinguished from one another by the extent of the scaling, and intensity of reddening of the skin, the mode of inheritance, and the different associated abnormalities. Some of the most common types are as follows:
- Ichthyosis vulgaris (most common)
- X-linked ichthyosis
- Ichthyosis bullosa of Siemens
- Lamellar ichthyosis
What causes ichthyosis?
Most known forms of ichthyosis are hereditary disorders; some are caused by dominant genes and others, by recessive genes.
In other forms of ichthyosis, skin cells either do not separate normally at the surface of the outermost layer of the skin, so they do not shed as quickly as they should, or they are overproduced in the epidermis. These cases result in a buildup of the scale characteristic of ichthyosis.
What are the symptoms of ichthyosis?
Symptoms of ichthyosis include the characteristic state of the skin. Patients will have scaly and dry skin over large areas of the body, namely on the trunk, stomach, legs, scalp, and buttocks. This skin may also itch and/or become reddened. The appearance of the scales varies: some may be fine and white and others may be dark and separated by deep cracks.
The most severe forms of ichthyosis can cause other associated problems, such as difficulty moving, skin abrasions, blocked pores, and ectropion (trouble closing eyes because the surrounding skin is so tight).
Babies who are born with some of the types of ichthyosis may be covered in a parchment-like membrane called a collodion membrane.
How is ichthyosis diagnosed?
A physician can often diagnose ichthyosis by simply looking at the skin. In some cases, however, a skin biopsy or genetic testing can be done to confirm the diagnosis.
What are the available treatments for ichthyosis?
Ichthyosis cannot be cured, but some treatments can help patients be more comfortable. Dry skin can be treated with skin softening lotions or salves containing alpha-hydroxy acids, urea, or propylene glycol. More severe cases of ichthyosis may be treated systemically with oral synthetic retinoids of Vitamin A.