Adenomyoma and adenomyomatous hyperplasia are benign tumor-like lesions that rarely involve the major or minor duodenal papilla. We report the case of a 73-year-old patient who underwent a cephalic duodenopancreatectomy due to clinical and radiological evidence of underlying malignant neoplasm. The histopathology results revealed the unusual association of a major duodenal papilla adenomyoma and an adenomyomatous hyperplasia of the minor papilla. Because of their resemblance to pancreatic malignancy, the diagnosis of these lesions is particularly challenging. In most cases, it is established postoperatively, after histopathological examination of the surgical specimen.