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by EBSCO Medical Review Board

Acanthosis Nigricans

Definition

Acanthosis nigricans is a skin problem that results in brown or black velvet-like markings. They appear under the arms, in the groin, or on the back of the neck. It can affect any skin fold.

Causes

Causes may be:
  • High insulin levels
  • Hormonal problems
  • Faulty genes
  • Cancer

Risk Factors

This problem is more common in people who are Native American, Black, or Hispanic. Other things that may raise the risk are:
  • Being overweight
  • Having a family history of this problem
  • Resistance to insulin
  • Taking certain medicines that cause insulin to rise too high

Symptoms

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

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done. It will focus on the skin. This is often enough to make the diagnosis.
If the diagnosis is not certain, a skin biopsy may be done.
Endoscopy
Endoscope in stomach
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Treatment

The underlying cause will need to be treated. Some choices are:
  • Maintaining a healthy weight through diet and exercise
  • Stopping or changing medicines that may be causing insulin problems
  • Medicines to improve skin appearance, such as topical and oral retinoids
  • Laser therapy to improve skin appearance

Prevention

To lower the risk of this problem:
  • Maintain a healthy weight through diet and exercise
  • Manage insulin levels

RESOURCES

American Academy of Dermatology
http://www.aad.org
NORD—National Organization for Rare Diseases
http://www.rarediseases.org

CANADIAN RESOURCES

Canadian Dermatology Association
http://www.dermatology.ca
Health Canada
https://www.canada.ca

References

Acanthosis nigricans. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/acanthosis-nigricans. Accessed October 29, 2020.
Phiske MM. An approach to acanthosis nigricans. Indian Dermatol Online J. 2014 Jul;5(3):239-249.

Revision Information

  • Reviewer: EBSCO Medical Review Board James P. Cornell, MD
  • Review Date: 09/2020
  • Update Date: 04/28/2021