There are a a number of skin conditions that are associated with the disease of obesity. Acanthosis Nigricans is characterized as areas of thickened, dark, velvety discoloration in body folds and creases. Usually seen in the armpits, neck, under the breasts, in the skin folds of the abdomen and groin. The exact cause of it at the molecular level is not clear other than seen frequently with insulin excess in the case of benign conditions. This symptom can give a warning about health conditions that require further investigation.

Patients may assume excessive sweating and poor hygiene are the causes of this condition- both of which are incorrect.

Acanthuses Nigerians is caused by acanthosis and papillomatosis of the epidermis (the outer most layer of the skin)  pigmentation is usually not in this area,  rather than pigment-producing cells. The skin proliferation abnormalities in acanthosis nigrcans are frequently associated with hyperinsulinemia and insulin resistance. This probably presents the best understanding of the pathology behind it. It suggests that the layer of  skin gets thicker probably caused by some stimuli- as indicated above seen with insulin excess.

There are two forms of this condition: Benign and Malignant.

Benign forms are associated with obesity, insulin resistance, and type II diabetes.

Insulin resistance: Insulin is a hormone secreted by the pancreas that allows your body to process sugar. Resistance predisposes to type II diabetes.

Hormonal disorders: Hypothyroidism, Polycystic Ovarian Disease, and other endocrine disorders of adrenal glands are ovaries

Drugs: Certain drugs and supplements such as high-dose niacin, birth control pills, steroids, may cause acanthosis nigricans.

Malignant forms may be an indication of Gastro-intestinal cancer such as stomach, colon, or liver cancer.

Treatment: No specific treatment is available for acanthosis nigricans. Treating the underlying conditions may restore some of the normal color and texture to affected areas of skin.