“Ichthyosis.”  After hours, days, months, or even years of examinations, specialists, and testing, you finally have a diagnosis.  It can be a relief to have a name, but you may feel strong emotions:  Did I cause it?  I shouldn’t have ……  while I was pregnant.  I should have known.  These emotions are often compounded by confusion. Since all the ichthyoses are so rare, sometimes even the professionals will give you outdated or inaccurate information.

Your best defense in this situation is up-to-date and accurate information from a physician who has experience with ichthyosis.  Getting a correct diagnosis of the type of ichthyosis that affects your child will help you to best understand his or her condition and predict his or her current and future needs and the impact on your family.

The term ichthyosis derives from ichthys-, the Greek root for “fish.” The fanciful reference is to the skin’s scales, which some consider fish-like. Rather than a single disease, ichthyosis identifies a family of about 30 related disorders. The ichthyoses (plural) are a group of rare genetic skin diseases whose primary characteristics include dry, thickened, and scaly skin. In some forms, the skin blisters and peels, especially during infancy and childhood. Many people with ichthyosis have darkened, rough skin that can appear as scales separated by deep creases. Mild forms of the disorder, particularly mild forms of ichthyosis vulgaris, may go undiagnosed, misdiagnosed, or overlooked because a parent has it.

The characteristic thickened and scaling skin results from genetic defects in the body’s ability to make and maintain the outermost layer of the skin, the stratum corneum. These genetic errors result in one of two biological outcomes, depending on the type of ichthyosis. Either the body manufactures the stratum corneum too rapidly (up to 300% faster than normal), or the stratum corneum fails to shed (desquamate) properly from the surface of the skin. Because skin constantly renews itself, either of these two interruptions in the balance between the making of the skin and its shedding results in the main signs of ichthyosis: thickened, scaly, red skin.  In one form of ichthyosis, Netherton syndrome, the stratum corneum is too thin, rather than too thick.  Here the problem is one of too rapid shedding (desquamation).

Some infants with ichthyosis are born encased in a tight, shiny, cellophane-like membrane. This is called a “collodion” membrane, and it usually covers the entire body. Collodion is a descriptive term for the membrane, which is a sheet of stratum corneum cells that have failed to shed during development in the uterus. Therefore, infants must shed the membrane. They may do this within a few days, although the membrane may not completely disappear for several months.
 
The collodion membrane can vary tremendously in thickness, and the period during which it is shed may be a vulnerable time for the infant. As the membrane cracks, fissures may extend through layers of skin making the infant susceptible to infection.  Tightness around the chest and trunk, as well as around the nostrils, may make breathing difficult.  The tightness of the membrane may cause the fingers and toes to contract and may restrict blood flow.  The tightness of the membrane around the eyes may cause the eyelids to flip inside out (ectropion). This may also happen to the lips (eclabium). The effects of the tight membrane around the mouth may create difficulties with nursing.  Infants with collodion membranes may have problems with fluid and electrolyte balance, and are particularly at risk for hypernatremia (elevated blood levels of sodium). 

Babies with epidermolytic ichthyosis (EI) have fragile skin, which may blister severely in infancy. They may lose large amounts of their outer layer of skin (the epidermis) during the birth process. Their skin may also blister or tear away with the slightest trauma. After a few weeks of living in a protective environment to avoid infection, these babies will appear less raw and their skin will be less fragile.

Babies with other forms of ichthyosis may be born with reddened skin, or thick, cheesy-like scales, or even looking normal or relatively normal, although their skin will gradually take on an abnormally rough, cracked and dry appearance. Most types of ichthyosis are diagnosed sometime within the first year of life, but in some cases, especially with ichthyosis vulgaris (the most common form of ichthyosis), the disorder may go undiagnosed indefinitely since it may be so mild that it is just treated as “dry skin,” or as a family trait.

Conclusive diagnosis of an ichthyosis is based on a combination of visible signs, family history, microscopic analysis of a biopsied section of skin, biochemical tests, and today, for many forms of ichthyosis, genetic analysis. The four most prevalent types of ichthyosis are ichthyosis vulgaris (IV), ARCI-lamellar ichthyosis (LI)/congenital ichthyosiform erythroderma (CIE), recessive X-linked ichthyosis (RXLI), and epidermolytic ichthyosis (EI), which is sometimes called bullous congenital ichthyosiform erythroderma (bullous CIE).

The ichthyoses are genetic conditions. They result from alterations or mutations in genes. This means that ichthyosis is not contagious. Frequently, parents who are not affected with ichthyosis bear a child who is affected and this may cause confusion. FIRST publishes a booklet entitled Ichthyosis: The Genetics of Its Inheritance, which explains the patterns of inheritance for genetic disorders, and explains why parents do not necessarily need to have ichthyosis in order to have affected children. The Foundation’s booklet Ichthyosis:  An Overview describes the most common forms of ichthyosis and answers frequently asked questions.