Acanthosis Nigricans

Acanthosis Nigricans
Acanthosis Nigricans


Acanthosis nigricans (AN) is a skin disorder characterized by darker and thicker patches of skin within body creases and folds. The darkened patches are often described as “velvety” in texture.

Commonly Associated With

Skin pigment disorder or AN

Causes Of Acanthosis Nigricans 

AN can appear at random in healthy people. However, it can also be related to pre-existing conditions, such as:

Hormonal disorders, including diabetes or obesity.

Some medications, such as prescribed human growth hormone or birth control pills.

Genetic disorders, such as Alström syndrome or Down syndrome.

Various cancers, including cancers of the digestive system, kidneys, liver, lymphatic system, or bladder

Symptoms Of Acanthosis Nigricans

AN usually onsets somewhat slowly, and doesn’t tend to cause any additional symptoms besides the changes to the skin.

Over time, darkened skin with a velvety texture will begin to become highly visible in various highly creased areas. These areas include neck folds, the groin area, and over the joints of the toes and fingers.

In some cases, AN affects the palms, soles of the feet, lips, or other areas. Patients with cancer of some type often see changes to the skin in more unusual areas.

Exams and Tests For Acanthosis Nigricans 

A health care provider can usually diagnose AN by examining the skin. In rare cases a skin biopsy may be necessary.

When there is no clear cause for the AN, a health care provider may order additional tests. These can include:

Treatment Of Acanthosis Nigricans 

No particular treatments are available for AN, as it is relatively benign. AN causes a change to the skin’s appearance, nothing more. If the changes become bothersome, the patient can try using various moisturizers. The best choice of brands for AN contain tretinoin, ammonium lactate, or hydroquinone to help lighten the appearance of the skin. A health care provider can also prescribe a laser treatment for the skin.

Addressing underlying health problems is crucial to the treatment of AN. For example, losing weight can improve AN in some cases.

Outlook (Prognosis)

When the underlying cause of the AN (if there is one) is treated or cured, AN often resolves on its own.

When to Contact a Medical Professional

Contact a health care provider if you or a loved one develops darkened areas of thick and/or velvety skin.