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 of acanthosis nigricans may include:
- High insulin levels in people who are obese
- A family history of acanthosis nigricans
- A cancerous tumor—rare
Acanthosis nigricans is more common in people of African-American decent. Other factors that may increase your chance of acanthosis nigricans include:
Symptoms include velvety-looking, dark areas anywhere on the skin.
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:
- 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 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.
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
American Academy of Dermatology
NORD—National Organization for Rare Diseases
Canadian Dermatology Association
Acanthosis nigricans. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 11, 2014. Accessed September 2, 2015.
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;68(10):1963-1968.
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.
Last reviewed September 2015 by James Cornell, MD
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.