Keratosis Pilaris

By Kira Mayo

We’ve all seen them–those little bumps on the back of the arms or front of the thighs. There’s a good chance that either you or someone you know has keratosis pilaris. While the cause is unknown, it can be genetic and often runs in families. Multiple small, pointed bumps appear mainly on the upper arms, thighs and buttocks. While it tends to improve with age, some people have lifelong keratosis pilaris with periods of remissions and exacerbations.

Who gets it?

Keratosis pilaris affects nearly 50-80 percent of all adolescents and approximately 40 percent of adults, making it primarily a condition of childhood and adolescence. It tends to occur more commonly in women than men. Additionally, about 30-50 percent of patients have a positive family history.

What causes it?

There is no clear cause of keratosis pilaris. It is thought to be due to a build up of skin cells around individual hair follicles. The bumps are caused by a hair that is unable to reach the surface of the skin after becoming trapped beneath the accumulated skin cells.

Why does it occur?

Truthfully, no one really knows why keratosis pilaris occurs, making it difficult to prevent and cure. What we do know is that dry skin in winter tends to worsen symptoms, so the condition often improves during the summer. In fact, keratosis pilaris is often seen in association with conditions that cause dry skin.

Signs & Symptoms

Those with keratosis pilaris often notice a rough texture, usually on the upper outer arms, front thighs and buttocks. The problem is mainly cosmetic, although it can be itchy for some. On physical exam, many small, slightly rough bumps are seen. It tends to have a sandpaper like texture, and may be associated with redness. In some cases, scratching away the surface of the bumps may reveal a small, coiled hair. Keratosis pilaris does not cause any medical problems, and is frequently noted in otherwise healthy, asymptomatic patients visiting their dermatologist for unrelated skin conditions.


While there are no specific lab tests that will diagnose keratosis pilaris, a dermatologist can perform a clinical exam and confirm a diagnosis based on its typical skin appearance in areas such as the upper arms and thighs. A family history of keratosis pilaris can also be helpful because of its strong genetic component.


Alai NN, Keratosis Pilaris. Available at: Accessed May 26, 2010

Originally written for DermHub


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