Ampullary and Pancreatic Neuroendocrine Tumors: A Series of Cases and Review of the Literature.

The ampulla of Vater is a unique, highly vascularized pouch. Its anatomic transition is halfway along the second part of the duodenum from the foregut to the midgut. According to the World Health Organization's (WHO) latest nomenclature, carcinoid tumors are now called neuroendocrine tumors (NETs). Knowledge of NETs is important because of their rarity, reclassification, prognosis, and management. NETs involving the ampulla of Vater are extremely rare, constituting <0.05% of gastrointestinal NETs, and involving the pancreas are rare to our knowledge. There are only a few reports of ampullary NETs. We report two rare NET cases involving the ampulla and pancreas and review the relevant literature. A 71-year-old patient with neurofibromatosis and multiple comorbidities presented with chronic intermittent abdominal pain. Abdominal imaging studies showed a suspicious mass at the level of the ampulla. Endoscopic retrograde cholangiopancreatography and endoscopic ultrasound revealed bulging papillae. Histopathology of the biopsied mass revealed a low-grade NET. Given his multiple comorbidities, the patient was scheduled for endoscopic resection. Our second patient was an 83-year-old lady presenting with nausea and vomiting. Abdominal imaging studies revealed a lobular mass over the body of the pancreas. Histopathological examination of fine-needle aspiration of the mass confirmed a well-differentiated low-grade NET. Octreoscan and dotatate scans showed pancreatic, multiple hepatic and metastatic lesions in the left lung and left shoulder. The patient is currently stable after completing peptide receptor radioligand therapy at a tertiary oncology center. Because of the patients' comorbidities and staging, their management has taken different approaches. More data and more research are needed for accurate assessment of prognosis; however, a review of the latest literature recommends Whipple resection with lymphadenectomy for all ampullary NETs provided patients can tolerate the procedure. Endoscopic resection or surgical ampullary resection should be performed on contraindicated patients. The majority of ampullary and pancreatic NETs would have metastasized by the time patients sought treatment. Because of their rarity and ill-defined and highly variable presentation, NET diagnosis is always delayed and sometimes incidental; therefore, we emphasize the importance of early diagnosis and management to reduce mortality and morbidity.