Acanthosis Nigricans

Acanthosis nigricans (AN) is a disorder that may begin at any age, including birth. It causes velvety, light brown, black, or grayish markings on the skin. They are usually found on the:

  • Face.

  • Neck.

  • Armpits.

  • Inner thighs.

  • Groin.

AN can be noncancerous (benign) or associated with cancer (malignant). Most often, AN is a benign condition. Benign AN is primarily associated with being overweight. In young people, insulin resistance is the most common association with AN. Insulin is the hormone that controls your blood sugar. Insulin resistance occurs when the body does not use its insulin properly. Benign AN may cause social problems, since the person may appear as if he or she has poor hygiene.


Some people are born with AN. It is sometimes caused by a hormonal or glandular disorder, such as diabetes. Eating too much of the wrong foods, especially starches and sugars, raises insulin levels. Most patients with AN have a high insulin level. Increased insulin activates insulin receptors in the skin and forces them to grow abnormally. This may help cause AN. Reducing insulin by a special diet can lead to a rapid improvement of the skin problem.

Both sexes are affected equally. Rarely, AN is associated with a tumor. The type of AN associated with malignancy more often occurs in elderly people. However, cases have been reported in children with a rare kidney cancer called Wilms' tumor. Malignant AN affects all races equally.


AN usually does not cause symptoms. Most people who have AN are bothered primarily by its appearance.


When AN develops in people who are not overweight, medical tests are often done to find the cause. When AN is associated with malignancy, it is unusually severe. In those cases, AN can be seen in additional places, such as the lips or hands. AN associated with malignancy is linked to major problems because it is caused by the presence of a cancer. The tumor is often aggressive and destructive. Benign AN has a good outcome. It is easily treated with good results.


  • Treatment to improve the appearance of AN includes prescription medicines (retinoids, 20% urea, alpha hydroxy acids, salicylic acid).

  • If overweight, avoiding starchy foods and sugars that raise the insulin level can help. Losing weight will also help decrease the appearance of AN tremendously.

  • Oral medicines are available that help decrease high insulin.


  • If you are overweight, exercise and watch your diet to lose the extra weight.

  • Use medicines prescribed by your caregiver as instructed.


You develop an unexplained case of AN in adulthood.