Oral acanthosis nigricans as a marker of internal malignancy. A case report

Background: Acanthosis nigricans (AN) is a rare mucocutaneous condition tha t can involve the oral tissues. There are 2 clinical forms of AN. benign an d malignant. Benign AN is related to systemic diseases such as diabetes and obesity or can be induced by drugs such as systemic corticosteroids, nicot inic acid, estrogens, insulin, and fusidic acid. Malignant AN appears in as sociation with tumors such as lung, ovarian, breast, and gastric carcinoma. Methods: A rare case of malignant AN that initially manifested in the oral cavity of a 73-year-old patient is reported. Results: A bladder and lung carcinoma were detected following the diagnosis of AN. Conclusions: The diagnostic importance of oral AN is emphasized because, in our patient, its recognition led to the detection of 2 occult malignant tu mors.