Acanthosis nigricans (AN) is a skin condition that is recognizable by the dark, thick areas of skin it causes, mainly in the folds of the neck and armpits. This dermatosis is most often completely benign and associated with obesity, but it can also be a sign of an underlying disease such as a malignant tumor.

The appearance of darker, thicker, rougher and drier, but painless, areas of skin is characteristic of Acanthosis nigricans. Their color results from hyperpigmentation (increased melanin) and thickening from hyperkeratosis (increased keratinization). Wart-like growths can develop. These spots can appear on all parts of the body, but they preferentially affect the folds of the skin, at the level of the neck, armpits, groin and genito-anal parts. They are seen a little less frequently on the knees, elbows, breasts and navel. A precise diagnosis must rule out the hypothesis of Addison’s disease [[+ link]] which causes similar tasks.

Researchers suspect that acanthosis nigricans is a reaction of the skin’s resistance to too high levels of insulin, the hormone produced by the pancreas that regulates blood glucose. This insulin resistance can be associated with various disorders, including obesity and type 2 diabetes. In its mild form, the most common and known as pseudoacanthosis nigricans, these are skin manifestations associated with obesity and reversible with weight loss. Medicines could also be the cause of some cases, such as growth hormones or certain oral contraceptives.

Acanthosis nigricans can also be an outward and visible sign of an underlying, silent disorder. This malignant form is fortunately much rarer because the causal disease often turns out to be an aggressive tumor: it is observed in 1 in 6 patients with cancer, most often affecting the gastrointestinal system or the genitourinary system. -urinary. The average life expectancy of a patient with malignant AN is reduced to a few years. (000)

Men and women are equally concerned and acanthosis nigricans can appear at any age, but preferably in adulthood. Note that dark-skinned people are more frequently affected, so the prevalence of NA is 1-5% among whites and 13% among blacks. (1) This skin manifestation is observed in about half of adults with severe obesity.

The disease is not contagious. There are familial cases of AN, with autosomal dominant transmission (inducing that an affected person has a 50% risk of transmitting the disease to their children, girls and boys).

Treatment for mild AN involves reducing the level of insulin in the blood with an appropriate diet, especially since AN can be a warning sign of diabetes. In any case, it is necessary to consult a dermatologist in the event of the appearance of an area of ​​darker and thicker skin. When AN appears in a person who is not overweight, comprehensive examinations should be done to make sure that it is not related to the underlying presence of a tumor.