Acanthosis Nigricans Causes, Symptoms, Diagnosis, Treatment, Prevention

Acanthosis Nigricans Causes, Symptoms, Diagnosis, Treatment, Prevention

What Is Acanthosis Nigricans?

Acanthosis nigricans is a fairly common skin pigmentation disorder. The most notable sign of acanthosis nigricans is dark patches of skin with a thick, velvety texture. These patches may appear on the armpits, groin, neck, elbows, knees, knuckles, or skin folds. Lips, palms, and soles of the feet may also be affected.

Acanthosis Nigricans Causes, Symptoms, Diagnosis, Treatment, Prevention
Acanthosis nigricans may be a sign of a more serious health problem such as pre-diabetes. The most effective treatments focus on finding and resolving medical condition at the root of the problem. Fortunately, these skin patches tend to disappear after successfully treating the root condition.

Acanthosis nigricans is most common in Native Americans, blacks and Hispanics. There's no specific treatment for acanthosis nigricans. Treatment of underlying conditions may restore some of the normal color and texture to affected areas of skin.

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.

Who Is at Risk for Acanthosis Nigricans?

Acanthosis nigricans is seen in both men and women. It is most common in those who are overweight, have darker skin, and have diabetes or pre-diabetic conditions.

The frequency of acanthosis nigricans varies between ethnic groups, and appears in:
  • 1 percent of Caucasians
  • 6 percent of Latinos
  • 13 percent of African Americans
  • 34 percent of Native Americans
All ethnic groups are equally at risk of acanthosis nigricans when body mass index (BMI) is well above normal.

Symptoms of Acanthosis Nigricans

Skin changes are the only signs of acanthosis nigricans. You'll notice dark, thickened, velvety skin in body folds and creases — typically in your armpits, groin and neck. The skin changes appear slowly, sometimes over months or years. The affected skin may also smell bad or itch.

When to see a doctor

Consult your doctor if you notice changes in your skin — especially if the changes appear suddenly. You may have an underlying condition that needs treatment.

How Is Acanthosis Nigricans Diagnosed?

Acanthosis nigricans is easy to recognize by sight. Your doctor may want to check for diabetes or insulin resistance as the root cause. These tests may include blood glucose tests or fasting insulin tests. Your doctor may also review all your medications to see if they are a contributing factor.

It is important to inform your doctor of any dietary supplements, vitamins, or muscle-building supplements you may be taking in addition to your prescription medications.

In rare cases, your doctor may perform other tests such as a small skin biopsy to rule out other possible causes.

How is acanthosis nigricans treated?

Acanthosis nigricans is not a disease. It is a symptom of another condition that may require medical attention. Treatment is largely focused on addressing the root condition. If you are overweight, your doctor will advise you to lose weight. Your doctor may also prescribe medications to help bring your blood glucose under control.

If the condition is caused by medications or supplements, your doctor may have you discontinue them or suggest substitutes. Generally the discolored skin patches will fade when you find the root cause and get it under control.

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.

Take medications. Symptoms may be relieved by treatment for underlying problems with your ovaries, adrenal glands or thyroid.

Surgery. If acanthosis nigricans was triggered by a cancerous tumor, surgically removing the tumor often clears up the skin discoloration.

If you are concerned about the appearance of your skin or if the lesions become uncomfortable or start to smell bad, your doctor may suggest:

  • Prescription creams to lighten the affected areas
  • Antibacterial soaps or a topical antibiotic to reduce odor
  • Oral acne medications
  • Laser therapy to reduce the skin's thickness

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 avoiding medications that tend to cause or worsen the condition (like birth control pills).