Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

Acanthosis Nigricans

Pronounced: AAY-can-THO-sis NIG-ruh-cans
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:

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.

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

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:

  • 20% Urea
  • Alpha Hydroxyacids
  • Retin-A
  • Salicylic Acid

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:

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

Last reviewed: September 2011 by Ross Zeltser, MD, FAAD.

RESOURCES
CANADIAN RESOURCES
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.
  • 10/15/2010 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : Kong AS, Williams RL, Smith M, et al. Acanthosis nigricans and diabetes risk factors: prevalence in young persons seen in southwestern US primary care practices. Ann Fam Med. 2007;5(3):202-208. Kong AS, Williams RL, Rhyne R, et al. Acanthosis Nigricans: high prevalence and association with diabetes in a practice-based research network consortium—a PRImary care Multi-Ethnic network (PRIME Net) study. J Am Board Fam Med. 2010;23(4):476-485.