Lima Memorial Health System Logo
Approximate ER WAIT TIME

Health Library

Acanthosis nigricans

Acanthosis nigricans

AN; Skin pigment disorder - acanthosis nigricans


Acanthosis nigricans (AN) is a skin disorder in which there is darker, thick, velvety skin in body folds and creases.



AN can affect otherwise healthy people. It can also be related to medical problems, such as:

  • Genetic disorders, including Down syndrome and Alström syndrome
  • Hormone imbalances that occur in diabetes and obesity, often called insulin resistance
  • Cancer, such as cancer of the digestive system, liver, kidney, bladder, or lymphoma
  • Some medicines, including hormones such as human growth hormone or birth control pills




AN usually appears slowly and doesn't cause any symptoms other than skin changes.

Eventually, dark, velvety skin with very visible markings and creases appears in the armpits, groin and neck folds, and over the joints of the fingers and toes.

Sometimes, the lips, palms, soles of the feet, or other areas are affected. These symptoms are more common in people with cancer.


Exams and Tests


Your health care provider can usually diagnose AN by looking at your skin. A skin biopsy may be needed in rare cases.

If there is no clear cause of AN, your provider may order tests. These may include:

  • Blood tests to check blood sugar level or insulin level
  • Endoscopy
  • X-rays




No treatment is needed, as AN only causes a change in skin color. If the condition is affecting your appearance, using moisturizers containing ammonium lactate, tretinoin, or hydroquinone can help lighten the skin. Your provider may also suggest laser treatment.

It is important to treat any underlying medical problem that may be causing these skin changes. When AN is related to obesity, losing weight often improves the condition.


Outlook (Prognosis)


AN often disappears if the cause can be found and treated.


When to Contact a Medical Professional


Contact your provider if you develop areas of thick, dark, velvety skin.




Dinulos JGH. Cutaneous manifestations of internal disease. In: Dinulos JGH, ed. Habif's Clinical Dermatology. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 26.

Patterson JW. Miscellaneous conditions. In: Patterson JW, ed. Weedon's Skin Pathology. 5th ed. Philadelphia, PA: Elsevier; 2021:chap 20.

BACK TO TOPText only

  • Acanthosis nigricans - close-up

    Acanthosis nigricans - close-up


  • Acanthosis nigricans on the hand

    Acanthosis nigricans on the hand


    • Acanthosis nigricans - close-up

      Acanthosis nigricans - close-up


    • Acanthosis nigricans on the hand

      Acanthosis nigricans on the hand


    A Closer Look


      Self Care


        Review Date: 5/31/2022

        Reviewed By: Elika Hoss, MD, Assistant Professor of Dermatology, Mayo Clinic, Scottsdale, AZ. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

        The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
        © 1997- adam.comAll rights reserved.