Ichthyosis is the term for severe, persistent problems with dry skin that almost always start in childhood or infancy. Ichthyosis can be genetic (inherited) or can develop later in life. In a large majority of people with the disease, the cause is related to one or more genetic mutations. Ichthyosis is characterised by persistently dry, thickened, rough, fish scale skin. There are at least 20 varieties of ichthyosis, including inherited and acquired forms. Under normal circumstances, the body continuously renews its skin surface, building new skin cells and allowing older cells to be shed from the surface.
Ichthyosis disrupts this balance either because too many replacement skin cells are produced or because the new skin cells do not separate well from the skin surface when it is their time to drop off. The result is that skin cells accumulate into thick flakes that adhere to the body and can resemble fish scales.
Depending on the type of gene abnormality that causes ichthyosis, the skin can show different patterns of flaking. In most cases of ichthyosis vulgaris, for example, skin will flake over the majority of the body, but not on the inside surfaces of joints, in the groin area or on the face. Symptoms of all genetic types of ichthyosis are either noticeable at birth or appear during childhood. Symptoms may include: Severe dryness of the skin with thickening and flaking, which may be appear only in limited areas or may involve almost the entire skin surface. Mild itching of the skin. Body odor, because the spaces under and between skin flakes can harbor collections of bacteria or fungus. Wax buildup in the ears, causing hearing difficulties. Symptoms are usually worse in winter months and in dry climates, because warmth and humidity improve thesymptoms. More than half of people who have ichthyosis vulgaris also have allergic problems, such as allergic nasal congestion, asthma or eczema.
Inherited forms of ichthyosis occur as a result of a genetic mutation. The mutated gene is passed on from one generation to the next. However, within a family there may only be one person affected. This can happen if the gene is recessively inherited (you have inherited two recessive genes, one from each parent), or you are the founder of a spontaneously mutated gene. The mutated gene causes an abnormality in the normal lifecycle of skin. Whilst in most people, the growth, dying and shedding of skin happens unnoticed, people with ichthyosis reproduce new skin cells at a rate faster than they can shed it, or reproduce at a normal rate but the rate of shedding is too slow. Either way there is a build up of dry scaly skin.
Ichthyosis vulgaris, accounts for 95% of all ichthyosis cases. Inheritance is autosomal dominant i.e. it is passed from a parent to about half their children. Signs and symptoms of ichthyosis vulgaris usually become apparent within the first year of life. Ichthyosis vulgaris is one of the most common of the inherited skin disorders. It may begin in early childhood, before a child is 4 years old. In most cases one parent and one-half of the children will be affected. It usually disappears during adulthood, but may recur when elderly. The other main forms of inherited ichthyosis include lamellar ichthyosis, epidermolytic hyperkeratosis, and X-linked ichthyosis.
Ichthyosis and ichthyosis vulgaris are treated with lotions or ointments to soften the skin and soothe the itching. Special gels called keratolytics, which include salicylic acid, lactic acid, or urea, help to remove the dry scales on the surface of the skin. The gel also contains an agent to moisturize the skin underneath. Your doctor may recommend applying this medication, then covering the affected skin with a waterproof dressing to help the gel penetrate. It is important to treat cracks in the skin immediately with a topical antibiotic to prevent infection. Ointments and lotions containing vitamin A derivatives called retinoids may also help promote new skin growth in patients with ichthyosis.