DefinitionAcanthosis 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.
CausesCauses of acanthosis nigricans may include:
- High insulin levels in people who are obese
- A family history of acanthosis nigricans
- A cancerous tumor—rare
Risk FactorsAcanthosis nigricans is more common in people of African-American decent. Other factors that increase your chances of getting acanthosis nigricans include:
SymptomsSymptoms include velvety-looking, dark areas anywhere on the skin.
DiagnosisYou will be asked about your symptoms and medical history. A physical exam will be done. Your bodily fluids may be tested. This can be done with:
- Skin biopsy
- Blood tests
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TreatmentTreatment 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.
PreventionTo reduce your chances of getting acanthosis nigricans, take these steps:
- 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
National Organization for Rare Diseases
Canadian Dermatology Association
Acanthosis nigricans. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated December 10, 2010. Accessed August 8, 2014.
Clark N, Stulberg DL, et al. 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).
Katz AS, Goff DC, et al. Acanthosis nigricans in obese patients: presentations and implications for prevention of atherosclerotis vascular disease. Dermatol Online J. 2000;6(1):1.
10/15/2010 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Kong AS, Williams RL, 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, 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.
- Reviewer: Brian Randall, MD
- Review Date: 08/2014
- Update Date: 08/08/2014