Acanthosis nigricans is a skin disorder that results in velvety, light-brown-to-black markings that can occur in any location but mainly are found in the skin folds of the neck, armpits, groin, and under the breasts.

What causes acanthosis nigricans?

Acanthosis nigricans can affect otherwise healthy people, or it can be associated with certain medical conditions. Sometimes acanthosis nigricans is congenital (something a person is born with). It is more likely to be seen in people with darker skin. The most common type is found in conditions that are associated with an elevated insulin blood level, such as in diabetes and obesity. There are many other possible causes of acanthosis nigricans, including:

  • Addison disease, a condition caused by a deficiency of hormones from the adrenal gland
  • Disorders of the pituitary gland within the brain
  • Growth hormone therapy
  • Hypothyroidism (low levels of thyroid hormone caused by decreased activity of the thyroid gland)
  • Oral contraceptives
  • Some cholesterol medications, including nicotinic acid

Most people with acanthosis nigricans have an insulin level that is higher than that of people of the same weight who don't have acanthosis nigricans. Eating too much of the wrong foods, especially starches and sugars, and being overweight can raise insulin levels.

Rarely, people with certain types of cancer can also develop severe cases of acanthosis nigricans.

How is acanthosis nigricans diagnosed?

The condition can be diagnosed by a doctor through a medical history and physical examination. Blood work might be done to investigate the cause of acanthosis nigricans. Occasionally, a skin biopsy is performed to get a detailed look at the tissue in a laboratory if the diagnosis is not straightforward on physical examination.

How is acanthosis nigricans treated?

The most effective treatment is obtained through weight loss and exercise. Eating a healthy diet can help reduce circulating insulin and can lead to improvement, and sometimes resolution, of the skin problem.

Other treatments to improve skin appearance, including Retin-A, urea, alpha hydroxy acids, and salicylic acid prescriptions, may be helpful in some people. Dermabrasion or laser therapy may help to reduce the bulky portion of the affected skin.

Acanthosis nigricans caused by medicine may go away once the medication is stopped.

Can acanthosis nigricans be prevented?

When acanthosis nigricans is related to obesity, weight management is an important part of prevention. A diet that contributes to reduced insulin also can help prevent acanthosis nigricans.

Other preventive strategies include treating medical problems that are linked to acanthosis nigricans (such as hypothyroidism and diabetes) and avoiding medications that tend to cause or worsen the condition (like oral contraceptives).


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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 3/2/2015...#12168