Acanthosis Nigricans

How to Say It: AAY-can-THO-sis NIG-ruh-cans


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


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.


Endoscope in stomach
Copyright © Nucleus Medical Media, Inc.


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


To lower the risk of this problem:

  • Maintain a healthy weight through diet and exercise
  • Manage insulin levels


American Academy of Dermatology
NORD—National Organization for Rare Diseases


Canadian Dermatology Association


Acanthosis nigricans. EBSCO DynaMed website. Available at: 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: 4/28/2021

EBSCO Information Services is fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

To send comments or feedback to our Editorial Team regarding the content please email us at Our Health Library Support team will respond to your email request within 2 business days.