What to know about acanthosis nigricans

Acanthosis nigricans is a skin disease that gives darker and thicker skin. This occurs most often in the folds of the skin around the throat, groin and armpits. Other symptoms also include itching and an odor.

Nigricans with acanthosis have links to obesity and diabetes, and treatment involves addressing the underlying disorder. In rare cases, in people who have certain cancers, a malignant type of acanthosis nigricans can develop.

In this article we address the causes and symptoms of nigricans with acanthosis, and list some of the treatment options available.

Symptoms of acanthosis nigricans

Acanthosis nigricans can cause dark areas of skin
Acanthosis nigricans can cause dark areas of skin.
Image credit: Vassia Atanassova – Spiritia, 2017.

The main symptoms of acanthosis nigricans are the following:

  • Hyperpigmentation: This is when certain areas of skin become darker, or more pigmented, and may turn greyish, black, or brown.
  • Hyperkeratosis: This is when areas of skin become thicker and may take on a velvet-like appearance. Eventually, skin lines may become deeper and more noticeable, and wart-like growths can appear.

Acanthosis nigricans can also cause the following additional skin symptoms:

  • dryness
  • excessive roughness
  • itching
  • an unusual odor

Malignant nigricans with acanthosis can cause more severe and extensive changes in the skin than the benign (noncancerous) form.

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

Changes usually grow gradually on the skin. They may occasionally be present from birth but usually appear in childhood or adulthood. They can occur anywhere but usually affect the following:

  • anus
  • armpits
  • genitals
  • groin
  • back and sides of the neck

Less commonly, acanthosis nigricans develops on the:

  • back of the knees
  • front of the elbows
  • knuckles
  • lips
  • palms of the hands
  • soles of the feet
  • stomach
  • under the breasts

Causes

Acanthosis nigricans is not a disease in itself. It is then a symptom of an underlying condition. Changes in the skin occur when the skin cells start reproducing too quickly.

The following factors can cause acanthosis nigricans:

  • Insulin resistance: Acanthosis nigricans commonly affects people with obesity and insulin resistance, which is a situation 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.
  • Genetics: Hereditary acanthosis nigricans may be present from birth, but most people develop it during childhood or later in life.
  • Medication use: Taking medications, such as birth control pills, corticosteroids, or high doses of niacin, can lead to the onset of acanthosis nigricans. Some bodybuilding supplements may also cause this skin disorder.
  • Cancer: In rare cases, malignant acanthosis nigricans can occur in people with certain types of stomach cancer, including gastric adenocarcinoma, as well as other carcinomas and lymphomas.

Risk factors

People who are obese or have a hormonal disorder may have a higher risk of acanthosis nigricans.
Image credit: Madhero88, 2010.
People who are obese or have a hormonal disorder may have a higher risk of acanthosis nigricans.
Image credit: Madhero88, 2010.

Risk factors for acanthosis nigricans include:

  • Obesity. People who are overweight are more likely to be resistant to insulin or have diabetes. Research suggests that up to 74 percent of people who are obese may have this condition. Obesity-associated acanthosis nigricans may be higher in females.
  • Ethnicity. According to the American Academy of Dermatology, acanthosis nigricans is more common in people who are of African, Caribbean, Hispanic, or Native American descent.
  • Genetics. People with family members that have acanthosis nigricans are at a higher risk of developing the condition.
  • Having a hormonal disorder. Those with conditions that affect their hormones are more likely to get acanthosis nigricans than others.
  • Taking certain medications or supplements. Some medicines, including hormonal birth control and steroids, increase the risk of developing acanthosis nigricans.

Treatment and home remedies

Doctors usually continue treatment of the underlying condition. If this is regulated, changes to the skin always go away.

Treatments vary according to the underlying issue, and include:

Losing weight

People who have acanthosis nigricans due to obesity or insulin resistance can find that if they lose weight, their skin improves.

Loss of weight may boost the texture of the skin but discoloration may remain.

Stabilizing hormones

Acanthosis nigricans can resolve for people with hormonal disorders if they use medication, lifestyle changes, and other therapies to keep their condition under control.

Managing diabetes

Individuals with type 2 diabetes can need medication, daily monitoring of blood sugar levels and changes in diet and lifestyle. Once insulin levels become stable, acanthosis nigricans symptoms may resolve.

Avoiding certain medications

If particular drugs or supplements causes acanthosis nigricans, then a doctor may suggest avoiding them or moving to an alternative. In certain cases after the medication is discontinued, the skin will return to normal.

Treating cancer

Malignant acanthosis nigricans can clear up after a cancerous tumor has been surgically removed. Many cancer therapies include chemotherapy and radiation therapy.

Cosmetic procedures

To reduce the appearance or odor of acanthosis nigricans, some people try cosmetic treatments, such as:

  • prescription creams to lighten the skin or to soften thick and rough patches
  • laser therapy to reverse skin thickening or lighten the skin
  • antibacterial soaps
  • topical antibiotics
  • oral medications

Cosmetic treatments do not resolve the underlying cause of acanthosis nigricans,  they may improve the appearance of the skin until other treatments take effect.

When to see a doctor

Those who experience darkening of skin, thickening or other changes in skin should make an appointment to see their doctor. The changes are mostly innocuous but they can indicate a disorder needing treatment.

A doctor can diagnose acanthosis nigricans mostly simply by looking at the skin. Nonetheless, additional tests may be required to determine their underlying cause. Tests for Diagnosis include:

  • a biopsy, where a doctor removes a small skin sample to examine under a microscope
  • blood tests
  • X-rays

Acanthosis nigricans and cancer

 acanthosis nigricans may occur in people with certain cancers
In rare cases, acanthosis nigricans may occur in people with certain cancers.
Image credit: Vandana Mehta Rai MD DNB, C Balachandran MD, 2010.

Cancer-associated acanthosis nigricans, named malignant acanthosis nigricans, is rare.

Malignant acanthosis nigricans are most generally found in older adults, where they affect both genders equally.

When this occurs it most often affects people with abdominal cancers like:

In people with gynecological cancers, such as ovarian cancer, acanthosis nigricans occur rarely.

The symptoms of nigricans with malignant acanthosis are similar to those of the benign type but they may be more severe and widespread. They can also impact the area around the eyes and the mouth.

Acanthosis nigricans and diabetes

Acanthosis nigricans is associated with insulin resistance, which is common in people with diabetes or at risk of diabetes. Trinidadians research indicates the skin condition is common among people with diabetes, regardless of age , sex, and ethnicity.

Children who have acanthosis nigricans are at greater risk of type 2 diabetes later in life.

Summary

Acanthosis nigricans is a relatively common skin condition characterized by dark, thick, and velvety skin patches that have associations with diabetes and overweight.

Usually, acanthosis nigricans signify an underlying condition such as diabetes or a hormonal disorder. Rarely can it suggest an abdominal or gynecological cancer.

People who experience changes in the skin should contact their doctor for diagnosis and treatment. acanthosis nigricans usually clear up until the underlying condition is under control. Even then, cosmetic treatments may enhance the appearance of the skin and reduce odors.

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