• Friday July 10,2020

Acanthosis nigricans

Acanthosis nigricans is one of the pigment disorders. This leads to gray to dirty brown skin growths.

What is Acanthosis nigricans?

Acanthosis nigricans forms dirty brown or gray growths on the skin. Particularly affected parts of the body are the elbow area, neck, armpits and knees.

Acanthosis nigricans is a pigmentation disorder of the skin. It is also called black-witch skin. A typical feature of the disease is the dirty brown or gray growths that form on the skin. Particularly affected parts of the body are the armpits, the elbow area, neck and knees. Occasionally, the changes in the lumbar region and the soles of the feet, palms and lips.

Acanthosis nigricans is considered an indication of serious health problems. This includes primarily prediabetes. In both men and women, the pigmentation disorder can occur. It is most commonly seen in overweight people with darker skin. With a share of about 34 percent, primarily Native Americans are affected. However, the disease risk is the same for all ethnic groups with a significantly higher body mass index (BMI).


Typical skin patches of Acanthosis nigricans are the rapid proliferation of epidermis cells. The cause of this diseased skin cell growth is usually an increasing insulin level in the blood. In some people, taking certain medicines or causing cancer also causes the skin changes.

In most cases, acanthosis nigricans is caused by an excess of insulin within the blood. When eating it comes to the conversion of carbohydrates into sugar molecules such as glucose. While part of the glucose is used by the organism for energy consumption, the rest serves as a reserve. To use the glucose for energy insulin is required. Thus, the glucose can reach the body cells with the help of insulin. Overweight causes insulin resistance over the years.

The body is then no longer capable of normal consumption, which in turn results in the accumulation of glucose in the bloodstream. As a result, an increased insulin and blood glucose value occurs. Due to the excess insulin, the skin cells multiply increased. People who are dark-skinned have abundant melanin in their cells. As the melanin increases, the skin spots appear darker in color than in the adjacent skin areas.

For this reason, acanthosis nigricans is considered as an indication of diabetes mellitus (diabetes). But certain drugs come as a trigger of the black-wither skin in question. These may be growth hormones, birth control pills, supplements for muscle building or thyroid remedies. So all drugs affect the insulin level.

Other possible causes that are rare, however, are adrenocortical disorders such as Addison's disease, low thyroid hormone levels, pituitary gland disorders, ingestion of high niacin levels and gastric cancer.

Diseases with this symptom

  • insulin resistance
  • cancer
  • stomach cancer
  • pituitary adenoma
  • drug allergy
  • Diabetes_mellitus
  • Hypothyroidism
  • Pituitary anterior pituitary insufficiency
  • Adrenocortical insufficiency
  • hypopituitarism
  • high blood pressure
  • pituitary tumor
  • Posterior pituitary insufficiency

Diagnosis & History

In most people, the dark patches of skin are symmetrical in the armpit and groin area. In some cases they also occur on the hands and lips. A typical symptom is a light brown or gray-black discoloration of the skin, which then appears "dirty".

At the surface relief, which feels like velvet, there is at first a papillary hyperkeratotic coarsening. If acanthosis nigricans persists for a long time, the skin becomes increasingly rougher. Other complaints usually do not exist.

The diagnosis of acanthosis nigricans usually succeeds to an experienced doctor already with the naked eye. Important is a test for insulin resistance or diabetes mellitus as a possible root cause. For this purpose, a fasting insulin test or a blood glucose test can be performed.

Acanthosis nigricans also differentiates between a benign form ( Acanthosis nigricans benigna ) and a malignant form ( Acanthosis nigricans maligna ). In order to differentiate between the two types, the search for a primary tumor takes place. In this case, the carcinoembryonic antigen (CEA) and the alpha-1-fetoprotein are determined by laboratory chemistry. In addition, all patient medications should be checked to see if they affect the pigmentation disorder.

Complications are primarily to be feared in the case of malignant acanthosis nigricans, which occurs especially in the elderly. Thus, the disorder in the malignant form is much more pronounced than in the benign. The mean survival time for malignant acanthosis nigricans is two years. In contrast, the benign form of therapy is sufficient to trigger the underlying disease.


Acanthosis nigricans can be the cause of various complications. The skin disease initially leads to a change in the appearance of the skin, which is often accompanied by itching and pain in the groin and armpits. The neck, lips and hands can also be affected and turn gray-black over the course of the disease. Complications mainly arise from the coarsening of the skin surface, which sometimes severely limits the feeling in the affected regions and makes the skin more sensitive overall.

Acanthosis nigricans may subsequently develop into a malignant tumor disease associated with carcinomas of the stomach and a strong, usually painful pigmentation of the arms and legs. The consequences of these malignant forms of acanthosis range from itching and gastrointestinal complaints to extensive organ damage. Other complications depend on the cause of acanthosis nigricans. If the symptoms include obesity, diabetes mellitus or other endocrinopathy, the following symptoms are typical: hypertension, obesity and other dyslipidemia.

The blood sugar level is also elevated and so often causes a deterioration of the state of health. If acanthosis nigricans occurs as a dominant hereditary acanthosis nigricans benigna, the complications are less serious. After the illness, which often improves after puberty, only minor skin changes remain, while long-term complications are usually absent.

When should you go to the doctor?

Acanthosis nigricans refers to a pigmentation disorder of the skin. The symptom manifests itself above all under the armpits, in the elbow area, in the neck and in the back of the knees. Less common are soles, palms, lips and loins affected. Acanthosis nigricans is most commonly associated with diabetes mellitus and is also preferred in overweight individuals with a darker skin tone. Acanthosis nigricans is not a mere discoloration of the skin but a rapid proliferation of the epidermis cells.

The cause of acanthosis nigricans is almost always an increased blood insulin level due to insulin resistance. The increased insulin leads to the proliferation of skin cells. Apart from diabetes mellitus, Acanthosis nigricans is caused by a variety of medications, including birth control pills, thyroid medications, growth hormones, and muscle building supplements. Acanthosis nigricans is also thought to be associated with hypothyroidism, pituitary gland disorders, Addison's disease and gastric cancer.

Acanthosis nigricans exists as a benign and malignant form. Since the survival time in the malignant form is short at about two years, a doctor should be consulted immediately when Acanthosis nigricans occurs. Even a benign Acanthosis nigricans can still turn into a malignant tumor disease. In addition to the general practitioner, specialists such as the internist, dermatologist and oncologist may be considered for the treatment of Acanthosis nigricans.

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Treatment & Therapy

Acanthosis nigricans is not an independent disease. Rather, it is the symptom of another disease. For this reason, the treatment of the pigment disorder focuses on the triggering cause. If the patient is overweight, the doctor recommends reducing it. Not infrequently, the sufferer also receives medicines that can be used to normalize his blood sugar level.

If medications or dietary supplements are the originators of acanthosis nigricans, these are usually discontinued or replaced by other agents. In most patients, the dark patches of skin fade after successful root cause therapy. If the skin changes lead to severe aesthetic impairments, cosmetic treatments may also be useful.

So the ugly spots can be covered with special cosmetics. Likewise, a treatment with prescription skin brighteners is possible. Although these measures are less effective than the treatment of the root cause, at least alleviate it.

Outlook & Forecast

Acanthosis nigricans is benign in the majority of cases. However, this pigment disorder is always only a symptom of an underlying disorder. Therefore, the lesions improve only when the cause is eliminated.

In many cases there is insulin resistance, with the result that the pancreas produces more insulin. The increased insulin concentration causes increased formation of receptors in the skin cells, which in turn lead to the conspicuous skin pigmentation of acanthosis nigricans. Left untreated, insulin resistance can lead to Type II diabetes mellitus.

As a rule, the skin changes here are only an accompanying symptom, indicating the risk of diabetes. If insulin resistance can be reversed through weight loss, dieting and physical activity, skin pigmentation will also fade.

An insulinoma in the pancreas requires surgery. Although it is a benign tumor that causes constant food cravings, dizziness, impaired consciousness, sweating and weight gain. This can cause damage to the central nervous system. After a surgical procedure, besides these symptoms, acanthosis nigricans disappears.

Those lesions caused by the influence of drugs usually improve after discontinuation of the causative drugs. In rare cases, however, can also develop a malignant form of Acanthosis nigricans, which is usually associated with malignant gastric tumors.


To prevent acanthosis nigricans, a healthy lifestyle is recommended. These include a low-fat diet, regular exercise and the reduction of obesity.

You can do that yourself

In the presence of acanthosis nigricans, there are some measures that the patient can perform himself to get rid of the ugly pigmentation disorders of the skin or at least mitigate. Since the cause of the skin discolorations is usually an increased insulin level, everything should be done to reduce it. Increased insulin levels are often associated with obesity, insulin resistance, or Type II diabetes mellitus. It can be lowered through weight loss, lots of exercise and a balanced diet. At the same time, the dark pigment spots usually fade.

However, if these measures do not help, it should also be examined whether it could be due to medication or additional preparations for muscle building. Amongst other things, growth hormones, pill or thyroid preparations are considered medications. Some preparations, such as the muscle growth supplements, could be discontinued by the patient himself. In most other cases, however, the doctor should be consulted.

If no action is taken, there may be serious illnesses that only a doctor can treat. These include tumors in the pancreas (insuloma), which continually produce insulin, malignant tumors in the stomach or hormonal disorders. By treating the underlying disease then also disappears the pigment disorder.

In the case of a lengthy treatment, the unsightly spots may also be previously masked by cosmetic measures or lightened by freely available skin brighteners which contain urea, retin-A, salicylic acid and alpha-hydroxy acids.

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