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. Any skin fold can be affected, including the lower lip and chin.

Causes

Causes of acanthosis nigricans may include:

• High insulin levels in people who are obese
• A family history of acanthosis nigricans
• A cancerous tumor—rare

Risk Factors

Acanthosis nigricans is more common in people of African-American decent. Other factors that may increase your chance of acanthosis nigricans include:

• Being overweight
• Type 2 diabetes
• Polycystic ovary syndrome

Symptoms

Symptoms include velvety-looking, dark areas anywhere on the skin.

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done.

Tests may include:

• Blood tests
• Skin biopsy if your doctor is concerned about skin cancer

Your bodily structures may need to be viewed. This can be done with:

• X-rays
• Endoscopy and colonoscopy—might be considered to screen for a rare malignancy associated with acanthosis nigricans if you are not obese or do not have diabetes

Treatment

Treatment often involves treating the underlying cause. For example, if acanthosis nigricans is due to obesity, weight loss can improve the skin condition.

Topical and oral retinoids and other medications have been reported to improve appearance in some cases. They help remove excess layers of skin.

Prevention

To reduce your chances of acanthosis nigricans:

• Maintain a healthy weight
• Eat a balanced diet
• Get regular exercise most days of the week
• Talk to your doctor about your blood sugar levels

NORD—National Organization for Rare Diseases http://www.rarediseases.org

Health Canada http://www.hc-sc.gc.ca

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Katz AS, Goff DC, Feldman SR. Acanthosis nigricans in obese patients: presentations and implications for prevention of atherosclerotis vascular disease. Dermatol Online J. 2000;6(1):1.

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.

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10/15/2010 DynaMed’s Systematic Literature Surveillance
http://www.ebscohost.com/dynamed:
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.