Acanthosis Nigricans

Acanthosis Nigricans

Acanthosis nigricans is a condition characterized by abnormal thickening and darkening of the skin, especially in the armpit and around the groin and neck. It is most commonly associated with obesity or polycystic ovarian disease in women, though acanthosis nigricans can occasionally be found in people who have more serious underlying health problems or who are taking certain medications. Treatment of the underlying medical condition usually resolves the skin lesions.

*Who's at risk?*

Acanthosis nigricans can affect individuals of any age, including children and those of any ethnic background. However, it is more common in adults and in people with darker skin. Males and females are affected equally.

Groups of people who commonly develop acanthosis nigricans:

Overweight or obese personsPeople with endocrine (glandular) abnormalitiesPersons taking certain medications (for example, oral contraceptives, niacinamide, corticosteroids)Kidney transplant patientsPeople with internal malignancy, especially stomach cancer (very rare cause of acanthosis nigricans)

*What causes acanthosis nigricans?*

Acanthosis nigricans sometimes occurs in people who are otherwise in good health, particularly dark-skinned people of African descent. However, in most cases it's a sign of an underlying problem or condition such as obesity, diabetes or abnormal hormone levels. Some of the main causes of acanthosis nigricans are outlined below.

*Obesity*

Acanthosis nigricans is usually the result of obesity. This is known as obesity-associated acanthosis nigricans.

It occurs because obesity can cause insulin resistance (when the body is unable to properly use the hormone insulin), which may lead to high levels of insulin in the blood, affecting the skin cells.

Insulin resistance can also cause type 2 diabetes, so acanthosis nigricans can be an early sign that you have diabetes or are at risk of developing the condition

*Syndromes and hormone problems*

Acanthosis nigricans is sometimes associated with an underlying syndrome or hormone problem, such as:

polycystic ovary syndrome - a condition that affects how a woman's ovaries work, which can cause excessive body hair, irregular periods, infertility, acne and weight gainCushing's syndrome -symptoms such as weight gain, bruising and stretch marks caused by very high levels of the hormone cortisol in the bodyacromegaly -where the body produces too much growth hormone, leading to the excess growth of body tissues over timeunderactive thyroid (hypothyroidism) -where your thyroid gland does not produce enough hormones, causing symptoms such as tiredness and weight gainThis type of acanthosis nigricans is known as syndromic acanthosis nigricans.

*Medication*

Acanthosis nigricans is sometimes triggered by medicines, including insulin, corticosteroids, and hormone treatments such as human growth hormone or the contraceptive pill. This is known as drug-induced or medication-associated acanthosis nigricans.

*Genes*

In rare cases, acanthosis nigricans can be caused by a faulty gene inherited directly from your parents. This is known as familial or benign genetic acanthosis nigricans.

This type is usually passed on in an autosomal dominant pattern, which means it can be passed on if only one of your parents carries the faulty gene.

*Cancer*

If the dark skin patches come on suddenly and spread quickly, it may be a sign you have cancer (usually stomach cancer). This is known as malignant acanthosis nigricans. This is a rare condition that tends to affect middle-aged or elderly people, regardless of their weight or ethnic background. The patches are more severe and the mouth, tongue and lips may also be affected. The skin may also become irritated and itchy.

*Signs and Symptoms*

Dark, velvety patches

If you have acanthosis nigricans, you'll have thickened, brownish-grey or black patches of skin. 

The patches will be dry and rough, feeling similar to velvet. They may also be itchy. 

These patches may occur anywhere, but are usually seen around the neck, in the armpit, around the groin and sometimes in other skin folds. Occasionally, the skin over the joints of the fingers and toes may be affected, as well as the lips, palms of the hands and soles of the feet. 

The patches usually develop slowly over time. Patches that grow and spread quickly are more likely to be associated with cancer. In these cases, the mouth, tongue, throat, nose and windpipe may also be affected.

*Tiny growths on the skin*

You may also have lots of tiny finger-like growths from the patches. This is known as papillomatosis.

There may also be skin tags around the affected area. These are small flesh-coloured or pigmented growths that hang off the skin and look a bit like warts.

*Self-Care Guidelines*

Because most people who develop acanthosis nigricans are overweight, their skin lesions can improve dramatically and even resolve with weight loss. Other underlying medical conditions should be treated as well. 

*Other treatments that might help include:*

Weight loss by changing dietary and exercise habits.Over-the-counter preparations containing alpha-hydroxy acids, such as glycolic acid or lactic acid.Over-the-counter lotions containing salicylic acid.Over-the-counter creams containing urea.Over-the-counter cortisone cream (if the areas are itchy).

*When to Seek Medical Care*

If you notice thickening and darkening of the skin folds, it is probably a good idea to see your primary care provider. If the acanthosis nigricans is due to obesity, then you can have medical assistance developing healthy strategies to attain your weight goals. 

The sudden development of widespread acanthosis nigricans (involving the skin folds as well as the palms of the hands, the lips, and other, less typical areas) should prompt immediate medical attention. The doctor may be able to diagnose and treat a more serious underlying medical condition that is causing the acanthosis nigricans.

*Treatment*

The doctor will certainly try to establish the underlying cause of the acanthosis nigricans. If it is due to obesity, then assistance with weight loss may be in order. If obesity is not a factor, the physician may try to determine an underlying cause by ordering blood work, X-rays, or other diagnostic tests. 

Once the underlying medical condition has been established and is being treated, your physician may recommend a topical cream or lotion containing the following:

Prescription-strength alpha- or beta-hydroxy acids (glycolic acid, lactic acid, salicylic acid)Prescription-strength ureaA retinoid such as tretinoin, tazarotene, or adapaleneFor more severe, stubborn acanthosis nigricans, oral treatments may include:Dietary fish oilsIsotretinoin, a very strong medication with many potential side effects, usually used in the treatment of severe, scarring acneNot usually covered by insurance, some procedures to treat acanthosis nigricans include:Dermabrasion, a mechanical process of controlled, surgical scraping of the skinLasers that thin the skin by destroying the uppermost layers

*Outlook*

Most cases of acanthosis nigricans are harmless and not a sign of anything serious. The skin patches often fade with time as the underlying condition is treated. 

If you have inherited acanthosis nigricans from your parents, your patches may gradually get bigger before staying the same or eventually fading on their own. 

Only in cases where there is underlying cancer is the situation very serious. If the tumour is successfully treated, the condition may disappear, but unfortunately the types of cancer that cause acanthosis nigricans tend to spread quickly and a cure is often not possible.