Acanthosis nigricans (AN) 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.
AN may be caused by:
- High insulin levels
- Hormone problems
- Gene issues
AN 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 medicines that cause insulin to rise too high
Symptoms of AN are velvety-looking, dark areas. These can appear anywhere on the skin.
The doctor will ask about symptoms and health history. A physical exam will be done. It will focus on the skin. This is often enough to make the diagnosis.
A skin biopsy may be done.
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The underlying cause of AN will need to be treated. Some choices are:
- Keeping a healthy weight with diet and exercise
- Stopping or changing medicines that may be causing insulin problems
- Medicines to help with skin appearance, such as topical and oral retinoids
- Laser therapy to help skin appearance
To lower the risk of AN:
- Keep a healthy weight through diet and exercise
- Manage insulin levels
- Acanthosis Nigricans. DermNet NZ website. Available at: https://dermnetnz.org/topics/acanthosis-nigricans.
- Acanthosis nigricans. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/acanthosis-nigricans.
- Acanthosis nigricans: overview. American Academy of Dermatology website. Available at: https://www.aad.org/public/diseases/a-z/acanthosis-nigricans-overview.
- Phiske, M.M. An approach to acanthosis nigricans. Indian Dermatol Online J, 2014; 5 (3): 239-249.
- James P. Cornell, MD
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