Acanthosis nigricans.

Acanthosis nigricans (AN) is a well-defined skin disorder characterized by velvety hyperkeratotic macules that can be accompanied by various degrees of pigmentation. Other manifestations of AN are marked papillomatous growths and deep skin markings. These changes can affect the entire skin but preferentially are observed in the axilla, neck, genitals, and oral cavity. The presence of AN around and within the oral cavity as well as its well-known association with internal malignant conditions, especially adenocarcinoma of the stomach, and/or its association with insulin resistance, has prompted this review article, which emphasizes the oral manifestations of AN.