Acanthosis nigricans is a skin disorder characterized by poorly defined pigmentation of the skin, in which there is a brown to black colored, velvety skin in the folds and creases of the body. This can be due existing medical problem, or it can affect otherwise healthy people. Some cases are hereditary, and is most commonly found in people of African, Hispanic or Native American descent. This may be in part because the condition is easier to see on darker skin. Acanthosis nigracans is more common in obese patients and and it is also related to some endocrine disorders, diabetes and obesity-related insulin resistance. Some medicines, particularly birth control pills and human growth hormones, can cause acanthosis nigricans. People with gastrointestinal cancers or lymphoma can also develop severe cases of the disorder.
This condition is usually asymptomatic and it appears slowly, with an eventual development of dark, velvety skin in the armpits, neck folds, groin area and joints of the fingers and toes. Other areas of the body are less commonly affected, such as the palms, soles of the feet or lips. The markings on the affected skin are very visible, may become thickened and may also have a bad odor.
There are a few treatment options available, as acanthosis nigricans itself only affects the skin. Prescription creams may lighten the affected areas, and antibacterial soaps can reduce odor. Laser therapy may also reduce the thickness of the affected skin. However, because it is so often associated with other medical conditions, it is very important that the underlying medical problems be treated. When acanthosis nigricans is related to obesity, losing weight often improves the condition. If the medical cause of the condition is treated, the skin areas affected by acanthosis nigricans can improve.