what is acanthosis nigricans
Acanthosis nigricans (AN) is a skin disorder in which there is darker, thick, velvety skin in body folds and creases. This condition usually appears slowly and doesn't cause any symptoms other than skin changes. Eventually, dark, velvety skin with very visible markings and creases appears in the armpits, groin and neck folds, and over the joints of the fingers and toes.