Acanthosis nigricans is a skin condition characterized by areas of dark, velvety discoloration in body folds and creases. The affected skin can become thickened. Most often, acanthosis nigricans affects your armpits, groin and neck.
The skin changes of acanthosis nigricans typically occur in people who are obese or have diabetes. Children who develop the condition are at higher risk of developing type 2 diabetes. Rarely, acanthosis nigricans can be a warning sign of a cancerous tumor in an internal organ, such as the stomach or liver.
No specific treatment is available for acanthosis nigricans. Treatment of underlying conditions may restore some of the normal color and texture to affected areas of skin.