What is Acanthosis Nigricans ?
Acanthosis Nigerians (AN) is a skin condition that is recognized by the dark, thick areas of skin that it causes, mainly in the folds of the neck and armpits. This dermatosis is most often benign and associated with obesity, but it can also be a sign of an underlying disease such as a malignant tumor.
Symptoms of Acanthosis Nigricans
The appearance of darker, thicker, rougher and drier skin areas, but painless, is characteristic of acanthosis nigricans. Their color results from hyper pigmentation (increase of melanin ) and thickening of a hyperkeratosis (increase of the keratinization ). Growths similar to warts may develop. These tasks can occur on all parts of the body, but they preferentially affect the folds of the skin, the neck, armpits, groin and genito-anal parts. They are observed less frequently in the knees, elbows, breasts and navel. A precise diagnosis must rule out the hypothesis of Addison’s disease causing similar tasks.
The origins of the disease
Researchers suspect that acanthosis nigricans is a skin resistance reaction to too high insulin levels, the hormone produced by the pancreas that regulates blood glucose. This insulin resistance may be associated with various disorders, including obesity and type 2 diabetes . In its benign form, the most common and known as pseudoacanthosis nigricans , there are skin manifestations associated with obesity and reversible with weight loss. Drugs may also be the cause of some cases, such as growth hormones or some oral contraceptives.
Acanthosis Nigerians may also be the external and visible sign of an underlying and silent disorder. This malignant form is fortunately much rarer because the causal disease often proves to be an aggressive tumor: it is observed in 1 in 6,000 patients with cancer, most often affecting the gastrointestinal system or genito -urinary. The average life expectancy of a patient with malignant NA is reduced to a few years. (1)
Men and women are equally involved and acanthosis Nigerians may appear at any age, but preferably in adulthood. It should be noted that people with dark skin are more frequently affected, so the prevalence of NA is 1-5% among whites and 13% among blacks. (1) This coetaneous manifestation is observed in approximately half of adults with severe obesity.
The disease is not contagious. There are familial cases of NA, with autosomal dominant transmission (inducing a 50% chance of transmitting the disease to its children, girls and boys).
Prevention and treatment
The treatment of benign AN is to reduce the level of insulin in the blood by means of a suitable diet, especially as the AN may be a warning sign of diabetes. In all cases, it is necessary to consult a dermatologist in the event of a darker and thicker area of skin. When NA appears in a person who is not overweight, complete examinations must be performed to ensure that it is not related to the underlying presence of a tumor.