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:
Acanthosis nigricans is more common in people of African-American decent. Other factors that may increase your chance of acanthosis nigricans 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:
Your bodily structures may need to be viewed. This can be done with:
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:
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.
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Last reviewed September 2015 by James Cornell, MD
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