Acanthosis Nigricans


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

Risk Factors

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:

  • 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
Endoscope in stomach
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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


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