Keratosis follicularis (KF) is a rare, inherited disorder that is characterized by hardened, wart-like skin lesions. Lesions may spread and become larger over time. They may also get better for periods and return due to things like humidity and heat. In some cases, lesions may group together and develop a strong, unpleasant smell. They are often itchy. Red and white streaks or lines are often present in the fingernails.
KF is genetic. Symptoms usually appear in some form before the age of 30. The disorder is also called Darier disease or Darier-White disease.
KF is caused by mutations in the ATP2A2gene. According to the New Zealand Dermatological Society, if one parent carries the abnormal gene then their child has a 50 percent chance of inheriting the gene (NZDS, 2012). However, people may have the abnormal gene and not experience noticeable symptoms. KF is not contagious.
The disorder can flare up and become worse due to summer heat, UV light, skin injury, and certain kinds of medication. Friction from rubbing, scratching, and tight clothing can also worsen symptoms.
Symptoms may be mild to severe, and can vary depending on environmental factors. Common symptoms of KF include:
- thick, rough skin lesions on the forehead, upper arms, chest, back, back of ears, knees, and elbows
- patches of moist skin that have a brownish or yellow crust
- irregular streaks in the nails that are red and white
- nails that chip in a split “V” shape
- little pits in the soles of feet and/or palms of hands
Lesions may be dry and itchy or greasy and crusty. They may have a strong smell, especially if they form in the folds of the skin (under the breasts, buttocks, armpits, etc.).
A physical diagnosis is necessary to diagnose keratosis follicularis. Your doctor or dermatologist will often ask about family history, because the disorder is inherited. The disorder is sometimes mistaken for Grover disease, which looks similar to KF—both cause small, red, bumpy spots on the skin. A skin biopsy, in which a sample of affected skin is removed and checked in a pathology lab, may be required in order to perform genetics tests or to have the skin sample examined under a microscope by a pathologist.
Keratosis follicularis is an ongoing disorder that varies in severity. For people with mild symptoms, KF can often be kept under control with moisturizer and sun protection.
If the disorder mostly affects one area, a skin smoothing technique called dermabrasion can be helpful. Dermabrasion is, at its most basic, sanding down the skin using sand paper or other mechanical means. In some cases dermabrasion is performed using lasers or carbon dioxide. It leaves the skin smooth, red, and raw, but it heals in a few days.
Topical retinoids (lotions and creams made from vitamin A) may be used to provide relief.
Oral retinoid medications such as acitretin or isotretinoin are sometimes prescribed in more severe cases. Oral retinoid medications can have unpleasant side effects. Some retinoids can cause spontaneous abortions, and is usually not recommended for pregnant women. Additional side effects can include depression, irritability, suicidal tendencies, dry lips and skin, and an increase in cholesterol levels.
Many people who have KF have mild symptoms that are not dramatically life altering. Even for those with severe symptoms, the disorder does not generally affect overall health. The disorder can often be managed by taking basic precautions such as staying out of intense heat and wearing loose clothing and sunscreen.
If your skin is infected by the herpes simplex (cold sore) virus, then a viral complication called eczema herpeticum can occur. Eczema herpeticum can aggravate the existing disorder and make the symptoms of KF worse. If you get cold sores, taking antiviral medication at the first sign of an outbreak can protect against viral complications.
Secondary bacterial infections, such as Staphylococcal (staph) infections, can also occur along with keratosis follicularis symptoms. Bacterial infections should be treated promptly with antibiotics.