How Are Ichthyosis and Dry Skin Linked?

What Is Ichthyosis?

Ichthyosis is a general term used to describe skin that is thickened, dry, scaly and flaky. Sometimes skin can be cracked and look like scales of a fish. “Ichthys” actually means fish in Greek. Ichthyosis is a result of abnormal maturation of the skin cells. Instead of flattening and slowly shedding as they mature, skin cells in people with ichthyosis have abnormal metabolism and do not shed off. Instead, the cells accumulate on the skin surface to form a thick layer.^[1]

There are several types of ichthyosis. Some are inherited and present at birth while others develop later in life. Ichthyosis that develops later in life can be a sign of internal diseases such as:^[2]

• Autoimmune disorders such as sarcoidosis
• Hormonal disorders such as thyroid diseases and diabetes
• Infections such as HIV and tuberculosis
• Cancer such as lymphomas and leukemias
• Medications such as cholesterol-lowering drugs and blood pressure medications

How Is Ichthyosis Linked to Dry Skin and Eczema?

Ichthyosis is similar to dry skin in that they both have a dysfunctional skin barrier. Normally, our skin barrier protects us from the harsh environment by preventing water from evaporating, keeping germs and allergic-causing chemicals out, and helps to keep moisture in. When this barrier is broken or not working normally, we end up with dry, thickened, and itchy skin that is prone to infection and inflammation.^[1,4]

The most common type of ichthyosis is called ichthyosis vulgaris (IV) and can be seen in 1 out every 300 people.^[5] People with IV typically develop ichthyosis early in childhood. They have fish-scale-like skin on the body, but most commonly on the lower legs and lower back. IV is closely linked to eczema, and up to half of the people with IV have clinical features of eczema or have relatives with eczema.^[6] Filaggrin is a protein that is important in maintaining the skin barrier: when the skin does not produce enough of it, the top layers of the skin become leaky. Genetic mutations in the filaggrin gene are found in both ichthyosis vulgaris and eczema.^[7]

Is Ichthyosis a Dangerous Condition?

Some rare inherited ichthyosis disorders can cause early death in a child. Some of these children are born with a clear membrane called the Collodion membrane that wraps around their body, which then sheds within a few days after birth. They later develop diffuse scaling and ichthyosis. Some may experience life-long abnormalities of the skin, nails, hair and occasionally internal organs.^[8] In babies with inherited ichthyosis, they can have increased water loss through the skin, which can cause life-threatening dehydration, electrolyte abnormalities, and heat loss.^[3] Some people with ichthyosis have trouble sweating and the thick scale prevents sweat from evaporating. As a result, they can become overheated easily. Some children with inherited ichthyosis have trouble absorbing nutrients through their guts and can have developmental and growth delays.^[9] In older children with severe types of ichthyosis such as Lamellar Ichthyosis, where the entire body is covered with thick scale, the movement of the joints can be affected and lead to long-term disability.^[10,11]

How Can Ichthyosis Be Treated?

Ichthyosis that develops secondary to another disorder (such as autoimmune disease and infections), may improve or resolve after the primary disease is treated. However, there is no cure for inherited ichthyosis and treatment is focused on controlling the symptoms. The main goals of treatment include skin hydration, lubrication, and removal of thick scales (keratolysis).^[3] Topical creams or moisturizers can be used to hydrate and lubricate the skin. Creams containing weak acids such as lactic acid, salicylic acid or urea can be used to soften the scales. A group of medications known as retinoids can also be used to help thin the excess dead skin. Retinoids can be prescribed as topical creams or as an oral pill. Topical steroids and calcineurin inhibitors can be used to treat cases associated with skin inflammation and itching. In severe cases of inherited ichthyosis, taking retinoids by mouth may be needed to decrease the thickness of the scale.^[12] 

In addition to routine dry skin care, people with ichthyosis should keep themselves hydrated to prevent dehydration, and keep cool to prevent overheating. Humidifying the environment is also beneficial.^[3,8,13]