Oral acanthosis nigricans in chronic hepatitis B with a 21-year follow up.

Acanthosis nigricans is a rare mucocutaneous disorder of unknown etiology that manifests as hyperpigmented velvety plaques, most often on intertriginous areas such as the neck and axillae as well as on mucosal sites such as the oral cavity. The disorder presents either as a paraneoplastic manifestation of an underlying malignancy, especially gastrointestinal adenocarcinomas or in association with obesity, administration of drugs or endocrinopathies, most commonly insulin-resistant diabetes mellitus. In the present article, a case of acanthosis nigricans with oral and cutaneous manifestations in a male patient with chronic hepatitis B infection is described. To the best of our knowledge, this is the first case of benign oral acanthosis nigricans associated with chronic hepatitis B.