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

Copyright © Nucleus Medical Media, Inc.

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.

Last reviewed September 2020 by EBSCO Medical Review Board James P. Cornell, MD  Last Updated: 10/29/2020