Acanthosis nigricans (uh-kan-THO-sis NIH-grih-kans)
A skin condition characterized by darkened skin patches. The condition is common in people whose body is not responding correctly to the insulin that they make in their pancreas (insulin resistance).
You may see this condition appear on the back of the neck, the arms, or the legs. Treating underlying conditions, such as obesity or a tumor, may restore the skin.