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Acanthosis nigricans
By Mayo Clinic staffMayo Clinic Health Manager
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Definition
Acanthosis nigricans is a skin condition characterized by dark, thick, velvety skin in body folds and creases. Most often, acanthosis nigricans affects your armpits, groin and neck.
With acanthosis nigricans, you may naturally be concerned about the appearance of your skin. Some steps may help lighten the affected areas of your skin. There's no specific treatment for acanthosis nigricans — but treating any underlying conditions, such as diabetes and obesity, may cause the changes in your skin changes to fade.
Symptoms
Characteristics of acanthosis nigricans include:
- Skin changes. Skin changes are the only signs of acanthosis nigricans. You'll notice dark, thick, velvety skin in body folds and creases — typically in your armpits, groin and neck. Sometimes the lips, palms or soles of the feet are affected as well.
- Slow progression. The skin changes appear slowly, sometimes over months or years.
- Possible itching. Rarely, the affected areas may itch.
Causes
Acanthosis nigricans is often associated with conditions that increase your insulin level, such as type 2 diabetes or being overweight. If your insulin level is too high, the extra insulin may trigger activity in your skin cells. This may cause the characteristic skin changes.
In some cases, acanthosis nigricans is inherited. Certain medications — such as human growth hormone, oral contraceptives and large doses of niacin — can contribute to the condition. Other hormone problems, endocrine disorders or tumors may play a role as well. Rarely, acanthosis nigricans is associated with certain types of cancer.
Risk factors
Acanthosis nigricans can begin at any age. It's most obvious in people who have dark skin.
When to seek medical advice
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.
Tests and diagnosis
Acanthosis nigricans is typically detected during a skin exam. Rarely, a small skin sample is removed (biopsy) for examination in a lab.
If the cause of acanthosis nigricans is unclear, your doctor may recommend blood tests, X-rays or other tests to look for possible underlying causes.
Treatments and drugs
There's no specific treatment for acanthosis nigricans. Treating any underlying conditions may cause the skin changes to fade, however. If you're overweight, losing excess pounds can help. Sometimes dietary changes are helpful, too.
Lightening affected areas
If you're concerned about the appearance of your skin, your doctor may prescribe a cream or lotion to help lighten the affected areas. Some of these lotions contain modified vitamin A products, such as tretinoin (Retin-A, others), or other medications. Sometimes oral medications, such as isotretinoin (Accutane, others), are helpful. Fish oil supplements also may be recommended. Dermabrasion or laser therapy may help reduce the thickness of certain affected areas.
