Acanthosis nigricans is a skin condition that results in
darkened skin and velvety growths that look like warts. These skin changes can
occur under the arm, on the back of the neck, or in the groin and genital
area.
In adults, acanthosis nigricans may rarely be a sign of
disorders of the hormone system (endocrine system) or being very overweight
(obese). It also may sometimes be a sign of digestive or lung cancer. It may
occur in people with type 2 diabetes and in people who are resistant to insulin
but have not yet developed type 2 diabetes. Acanthosis nigricans also may occur
in polycystic ovary syndrome (PCOS).
