In acanthosis nigricans, the skin becomes thick and velvety. Depending on the person’s skin tone, it may become darker, too. It is often a sign of an underlying condition, such as insulin resistance.

Acanthosis nigricans most often appears in skin folds around the neck, groin, and armpits. There may also be itching.

It is often the sign of an underlying condition and is more likely to occur if a person has obesity or diabetes or uses certain medications. In some cases, it can occur with cancer.

Treatment usually involves addressing the underlying disorder, although some cosmetic and topical approaches may help improve symptoms.

In this article, we discuss treatment options for acanthosis nigricans, as well as the symptoms, causes, and links with other conditions.

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There is no specific treatment for acanthosis nigricans.

While some cosmetic treatments may help, the most effective approach is to treat any underlying disorder. Addressing an underlying condition may cause symptoms to fade in time.

Treating the symptoms

To reduce the appearance of acanthosis nigricans, some people try topical or cosmetic treatments.

Examples of topical creams and ointments are:

Cosmetic procedures that may help include:

Other options that may help include:

Some of these treatments have helped improve symptoms in some people. However, the most effective approach is likely to be treating any underlying condition.

People should talk with their doctor before using any of these products.

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Treatment for underlying conditions

Treatment for an underlying condition will depend on the issue.

  • Hormone disorders: A treatment plan involving medication and lifestyle adjustments may help balance hormones and reduce symptoms of acanthosis nigricans.
  • Diabetes: People with type 2 diabetes may need medications, monitoring of blood sugar levels, and some dietary and lifestyle adjustments. Once insulin levels become stable, acanthosis nigricans symptoms may resolve.
  • Weight management: Obesity is a risk factor for insulin resistance and other aspects of metabolic disorder. Maintaining a moderate weight may help manage these conditions. In turn, skin symptoms may improve.
  • Avoiding certain medications: Some drugs, such as corticosteroids, can trigger acanthosis nigricans. Symptoms often resolve if the person stops using the drug.

Treatment for malignant acanthosis nigricans includes surgical removal of a cancerous tumor. Other treatments a person may need are chemotherapy and radiation therapy.

If acanthosis nigricans results from a hereditary disorder, the patches may grow slowly then stop or reduce in size without treatment. However, the changes will remain in most cases while the underlying condition is present.

Treating the underlying condition may improve symptoms of acanthosis nigricans. If a person with obesity loses weight, the patches may fade. However, changes in color may not disappear completely.

Treating skin symptoms will not make the lesions disappear. However, it may help improve the appearance.

Acanthosis nigricans often indicates that an underlying disorder is present. The changes take place when certain skin cells reproduce too quickly, leading to hyperpigmentation and hyperkeratosis.

Hyperpigmentation is when pigment increases in certain areas of skin, making them darker.

Hyperkeratosis is when the outer layer of skin becomes thicker due to the body producing extra keratin.

Learn more about pigmentation in the skin.

The following factors can cause acanthosis nigricans:

Insulin resistance

Acanthosis nigricans commonly affects people with obesity and insulin resistance, where the body cannot use insulin effectively. Insulin resistance eventually leads to type 2 diabetes.

Hormonal changes

People with hormonal disorders, such as Addison’s disease, polycystic ovary syndrome (PCOS), or hypothyroidism may develop acanthosis nigricans.

Genetic factors

Hereditary acanthosis nigricans may be present from birth. However, most people develop it during childhood or later in life.

Unilateral acanthosis nigricans, also called nevoid acanthosis nigricans, is an inherited condition that causes symptoms on one side of the body. Some insulin-resistant syndromes with genetic causes can cause it, such as Rabson Mendenhall syndrome.

Medication use

Drugs that may trigger acanthosis nigricans include:

Cancer

Acanthosis nigricans can develop with some types of cancer. Skin changes may appear before, during, or after internal symptoms become evident.

Some auto-immune conditions

People with lupus, Sjogren’s syndrome, scleroderma, or Hashimoto’s thyroiditis may develop acanthosis nigricans.

Other factors

According to the American Academy of Dermatology, people of Native American, Caribbean, African, or Hispanic descent are more likely to develop acanthosis nigricans.

The main symptoms of acanthosis nigricans are hyperpigmentation and hyperkeratosis. A person may notice changes in the color and texture of their skin. The color may become grey, black, or brown. The appearance and texture may become velvety.

The changes usually take months or years to appear. If they appear quickly, they could be a sign of cancer. The lesions may also be more widespread and more noticeable.

The person may also notice:

Some people experience these skin changes on one side of their body only. This is known as unilateral acanthosis nigricans.

Changes to the skin typically develop slowly. Occasionally, they can be present from birth. However, they usually appear in childhood or adulthood. They can occur anywhere but commonly affect the following:

  • armpits
  • neck folds, especially on the back and sides of the neck
  • genitals
  • groin
  • under the breasts
  • anus
  • knees
  • knuckles
  • elbows
  • belly button
  • palms of the hands
  • soles of the feet

In rare cases, typically those associated with malignancy, skin changes of acanthosis nigricans may appear on the:

  • areolae, around the nipples
  • mucous membranes, including those in the mouth, nose, and throat
  • part of the eye and eyelids

The following images show how acanthosis nigricans can appear on the skin.

Acanthosis nigricans can occur with some types of cancer, such as:

The symptoms of malignant acanthosis nigricans are similar to those of the benign form. However, they may be more severe and widespread and often develop more quickly. They can also affect the mouth and the area around the eyes.

Symptoms may appear before, during, or after other cancer symptoms.

Insulin resistance, a feature of type 2 diabetes, is linked to acanthosis nigricans. When people have insulin resistance, their bodies can no longer process glucose effectively.

The body produces more insulin in an attempt to manage this, resulting in high levels of both insulin and glucose in the body. These high levels of insulin can cause skin cells to reproduce more rapidly.

Research suggests that acanthosis nigricans may affect up to 74% of people with obesity and diabetes.

Dark patches on the skin may be an early sign of type 2 diabetes. Anyone who notices these skin changes should seek medical advice, as they may need treatment to prevent or manage type 2 diabetes.

Acanthosis nigricans often occurs with PCOS. It happens when there is an imbalance in reproductive hormones. Symptoms include irregular menstruation and weight gain.

PCOS is a reproductive and metabolic disorder, and people with this condition often have insulin resistance.

People with PCOS have a higher chance of developing acanthosis nigricans. Insulin resistance appears to be a major factor. However, having obesity at the same time can further increase the risk.

People who notice skin darkening, thickening, or other skin changes should make an appointment to see their doctor. The changes are often harmless. However, they can suggest a medical condition that needs treatment.

A doctor can often diagnose acanthosis nigricans by looking at the skin. However, they may need to perform additional tests, such as a biopsy, to confirm the diagnosis.

They may also do blood tests, imaging scans, and other investigations to identify an underlying cause.

Acanthosis nigricans involves skin changes leading to patches of dark, thick, and velvety skin. These may appear on the neck, underarms, skin folds, and other parts of the body.

Obesity and insulin resistance are risk factors. However, hormonal disorders, medication use, cancer, and other conditions can cause it.

People who notice skin changes should see their doctor, as they may need treatment for an underlying disorder. Treating an underlying condition may improve skin symptoms. Some topical and cosmetic treatments may also help.