Learn about the causes of and treatment for this condition that causes dark, velvety patches in folds of the skin.
Acanthosis nigricans is a condition that causes areas of dark, thick velvety skin in body folds and creases. It typically affects the armpits, groin and neck.
Acanthosis nigricans (ak-an-THOE-sis NIE-grih-kuns) tends to affect people with obesity. Rarely, the skin condition can be a sign of cancer in an internal organ, such as the stomach or liver.
Treating the cause of acanthosis nigricans might restore the usual color and texture of the skin.
The main sign of acanthosis nigricans is dark, thick, velvety skin in body folds and creases. It often appears in the armpits, groin and back of the neck. It develops slowly. The affected skin might be itchy, have an odor and develop skin tags.
Consult your health care provider if you notice changes in your skin — especially if the changes are sudden. You may have an underlying condition that needs treatment.
Acanthosis nigricans might be related to:
The risk of acanthosis nigricans is higher in people who have obesity. The risk is also higher in people with a family history of the condition, especially in families where obesity and type 2 diabetes are also common.
People who have acanthosis nigricans are much more likely to develop type 2 diabetes.
Acanthosis nigricans can be detected during a skin exam. To be sure of the diagnosis, your health care provider might take a skin sample (biopsy) to look at under a microscope. Or you may need other tests to find out what's causing your symptoms.
There's no specific treatment for acanthosis nigricans. Your care provider might suggest treatments to help with pain and odor, such as skin creams, special soaps, medications and laser therapy.
Treating the underlying cause might help. Examples include:
You're likely to start by seeing your primary care provider. Or you may be referred to a doctor who specializes in skin disorders (dermatologist) or hormone problems (endocrinologist). Because appointments can be brief and there's often a lot to discuss, it's a good idea to prepare for your appointment.
Before your appointment, you may want to list answers to the following questions:
Your health care provider is likely to ask you questions, such as the following: