Abstract
Adenomas of the ampulla of Vater are distinctly rare, representing <10% of periampullary neoplasms. Very few reports of the cytologic features of ampullary adenomas are present in literature, particularly in bile duct brushing samples. A case report and review of the literature is presented. The typical cytologic features of ampullary adenomas on cytologic preparations include tall, thin columnar cells with mildly hyperchromatic elongated nuclei and nuclear pseudostratification, in a relatively clean background. The key differential diagnostic entities include invasive adenocarcinoma, thermal artifact, and reactive atypia.