Neuroendocrine tumor of the ampulla of Vater showing chronological endoscopic changes

We report a rare case of neuroendocrine tumor of the ampulla of Vater in a 53-year-old Japanese male. The patient was admitted to our institution for workup of presyncope secondary to anemia. Medical history was pertinent for coronary artery disease, for which he had drug eluting stents (DES) placed and was on aspirin and clopidogrel therapy. Upper endoscopic evaluation revealed bleeding from an erosion at the ampulla of Vater. Endoscopic therapy with epinephrine and thrombin injection allowed for successful hemostasis and repeat endoscopy 6 months later did not show any changes in lesion character. Repeat endoscopy at 1 year, however, revealed erythema and further erosion on the ampulla of Vater as the lesion had progressed. The patient was diagnosed with carcinoma of the ampulla of Vater. Abdominal computed tomography showed a 9-mm hypervascular tumor at the ampulla of Vater and the patient underwent open pancreatoduodenectomy and lymphadenectomy. Histologically, the tumor consisted of small-sized round cell proliferations with a solid nest pattern. Immunostaining results indicated that the tumor cells were positive for synaptophysin and 2.5% were positive for Ki-67. The final diagnosis was sporadic non-functional neuroendocrine tumor (NET) G1 of the ampulla of Vater. This case demonstrates that NET of the ampulla of Vater, while rare, can have significant changes and growth over time and highlights the importance of follow-up endoscopic evaluations.