Acanthosis nigricans (AN) is a skin condition that causes increasingly thicker and darker patches or streaks around joints and body areas with many creases and folds (such as knuckles, armpits, elbows, knees, and the sides and back of the neck).

Some people also develop AN on their palms, groin, lips, or, in very rare cases, non-crease areas like the face, back, arms, or legs. The skin may stay soft, which is why the word "velvety" is often used to describe the symptoms of AN.

Acanthosis nigricans (ay-can-THO-sis NYG-ruh-cans) is not an infection and isn't contagious. A few kids might have mild itching, but otherwise AN itself is harmless. Still, a doctor will run tests to rule out underlying causes that could require treatment.

Managing AN means treating the conditions that are causing the skin darkening (known as hyperpigmentation).

Causes

The exact causes of acanthosis nigricans vary and are often unknown. In some cases, it can be hereditary, occurring in otherwise healthy children and teens. Although not dangerous in these cases, it can make kids self-conscious about their appearance.

AN is commonly found in children with elevated blood insulin levels, a condition often associated with kids who are overweight or obese or have diabetes.

Sometimes AN can be a warning sign of other more serious conditions, such as certain cancers and endocrine problems, along with type 2 diabetes and the health issues associated with obesity. In rare cases, AN can be caused by certain medications, such as oral contraceptives and cholesterol medications.

Symptoms

Usually, the only signs of AN will be dark, thick, velvety patches of skin in creases and folds, usually in the neck, armpits, or groin, but sometimes also the lips, palms, knuckles, soles of the feet, and other areas. In rare cases, children may have mild itching in the affected areas.

The patches of skin will usually change color slowly, over the course of months or even years. If your child's skin changes color rapidly, consult a doctor right away. It could be a sign of a serious medical condition.

Diagnosis

If your child develops AN, consult a doctor to determine whether there is a serious underlying condition. Doctors can generally make a diagnosis of acanthosis nigricans through a visual examination of the affected skin.

To test for other conditions, the doctor may order blood tests, or an X-rays.

Treatment

Most cases of AN only involve changes in skin color and thickening of skin, and there is no set treatment for it. For many kids, AN will require no treatment at all; for some, the dark skin will eventually fade on its own.

For cases of AN where an underlying cause is identified, treating the cause can make the dark patches of skin fade or disappear entirely. This can mean ceasing any medications that might be causing the problem or treating any health issues.

For most kids, the best treatment for AN is to maintain a healthy weight and get plenty of exercise. Encourage your child to eat a good diet and make healthy lifestyle choices. Several studies show that eating well and exercising can help lessen, and in some cases prevent or reverse, AN.

Living With Acanthosis Nigricans

Because AN can be highly visible and hard to cover up — especially if it occurs on the neck or hands — it can be both scary and embarrassing. Your child may feel extremely self-conscious and may be teased by classmates.

To help kids feel better about their appearance, doctors often prescribe creams and lotions that can help lighten the skin. Ask as many questions as you need to in order to understand when and how to follow the treatment plan.

Don't believe the hype about bleaches, skin scrubs, and over-the-counter exfoliating treatments — these aren't likely to work and can irritate the skin, not to mention waste money.

Maintaining a healthy weight by staying physically active and eating well can help prevent or treat acanthosis nigricans in some cases.

As a parent, you can do a lot to help your child minimize anxiety and feel less afraid and embarrassed about AN. Talk openly about AN and let your child know that he or she is not alone. Ask a doctor or medical professional about local support groups or other resources that can help your child feel more confident.

Reviewed by: Patrice Hyde, MD
Date reviewed: April 2013