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Acanthosis Nigricans by Diana Kohnle

Definition

Acanthosis nigricans is a skin condition in which brown or black velvet-like markings appear under the arms, in the groin, or on the back of the neck, but any skin fold, including that of the lower lip and chin, can be involved.

Causes

This condition is most often caused by being overweight, but can also, very rarely, be caused by the presence of a tumor.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.

Risk factors for acanthosis nigricans include being overweight, having unusually high insulin levels, or eating a diet rich in starches and sugars. People of African-American descent are also more likely to develop acanthosis nigricans than people of other racial derivation.

Symptoms

If you experience any of these symptoms, do not assume it is due to acanthosis nigricans. These symptoms may be caused by other health conditions. If you experience any one of them, see your physician.

Velvety-looking, dark areas on:
- Back of the neck
- Armpits
- Groin
- Elbow
- Knees
- Knuckles
- Face
- Palms
Acanthosis nigricans is often accompanied by skin tags .

Diagnosis

Your doctor will ask about your symptoms and medical history, and perform a physical exam. Tests may include the following:

Skin biopsy
Blood tests
Endoscopy to rule out other causes
X-rays to rule out other causes

Endoscopy

Treatment

In and of itself, acanthosis nigricans is not a life-threatening condition. However, high levels of insulin can lead to a condition known as hyperinsulinemia, which in extreme cases can cause hypoglycemia . This, in turn, can lead to insulin shock, coma, and death. Talk with your doctor about the best treatment plan for you.

The following topical treatments are used to reduce the appearance of markings:

Alpha Hydroxyacids
Salicylic Acid
Retin-A
20% Urea

Changes in diet also help to reduce the amount of insulin in the body.

Prevention

To help reduce your chances of getting acanthosis nigricans, take the following steps:

Maintain a healthy body weight.
Check insulin levels regularly and keep at a normal level.

RESOURCES

National Organization for Rare Diseases http://www.rarediseases.org/
US National Library of Medicine http://www.nlm.nih.gov/nlmhome.html/

CANADIAN RESOURCES

Dermatologists.ca http://www.dermatologists.ca/index.html/
Health Canada http://www.hc-sc.gc.ca/index-eng.php/

References

Clark N, Stulberg DL, Tovey D. Common hyperpigmentation disorders in adults: part II. Melanoma, seborrheic keratoses, acanthosis nigricans, melasma, diabetic dermopathy, tinea versicolor, and postinflammatory hyperpigmentation. Am Fam Physician. 2003 Nov 15;68(10). Available at: http://www.aafp.org/afp/20031115/1963.html . Accessed December 14, 2006.
Goff DC, Katz AS, Feldman SR. Acanthosis nigricans in obese patients: presentations and implications for prevention of atherosclerotis vascular disease. Dermatology Online Journal . 2000;5(1). Available at: http://dermatology.cdlib.org/DOJvol6num1/original/acanthosis/katz.html . Accessed December 14, 2006.

Last reviewed July 2010 by Rosalyn Carson-DeWitt, MD

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