Background: Acanthosis nigricans (AN) is a rare mucocutaneous condition that can involve the oral tissues. There are 2 clinical forms of AN: benign and malignant. Benign AN is related to systemic diseases such as diabetes and obesity or can be induced by drugs such as systemic corticosteroids, nicotinic acid, estrogens, insulin, and fusidic acid. Malignant AN appears in association 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 tumors.