Acanthosis Nigricans

  • 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
    • Rarely, a cancerous tumor
  • Risk Factors

    Acanthosis nigricans is more common in people of African-American decent. Other factors that increase your chances of getting acanthosis nigricans include:
  • Symptoms

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

    Your doctor will ask about your symptoms and medical history. A physical exam will be done. Tests may include the following:
    • Skin biopsy
    • Blood tests
    • X-rays
    • Endoscopy
    Endoscope in stomach
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  • 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 medicines have been reported to improve appearance in some cases. They help remove excess layers of skin.
  • Prevention

    To 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

    National Organization for Rare Diseases

    American Academy of Dermatology


    Health Canada


    Acanthosis nigricans. EBSCO DynaMed website. Available at: Updated December 10, 2010. Accessed June 3, 2013.

    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 : 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.

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