Acanthosis nigricans: A fold (intertriginous) dermatosis.

Acanthosis nigricans (AN) is a mucocutaneous disorder that is characterized by focal or diffuse hyperkeratotic, surfaces, which are symmetrically distributed hyperpigmented lesions of the skin. It rarely affects mucosal surfaces like oral cavities. Although it is commonly seen in adolescents, AN is also increasingly seen in children who are obese. Recent studies have found that AN can be a cutaneous indicator of insulin resistance and malignancy. Acanthosis nigricans has been associated with type 2 diabetes mellitus, obesity, endocrinopathies, drugs, and malignancies.