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

Abstract

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.

Keywords: ampullary carcinoids; ampullary mass; ampullary neuroendocrine tumors; gastrointestinal carcinoid tumor; pancreatic malignancy; pancreatic neuroendocrine tumor; pancreatic neuroendocrine tumors.

Figure 1. CT abdomen and pelvis with contrast showed a soft tissue density nodule seen at the level of ampulla measuring 1.2 cm X 1.1 cm (yellow arrowheads pointed towards density in the white circle) and common bile duct diameter measured 10 mm and the pancreatic duct was 4.5 mm at the level of the pancreatic head.

Figure 2. Magnetic resonance cholangiopancreatography (MRCP) showed a suspicious mass at the level of ampulla (yellow triangles).

Figure 3. Endoscopic ultrasound shows single intramural mass in the area of papilla.

Figure 4. ERCP showed abnormal bulging papillae with malignant appearing partially occluding mass present in the entire biliary tract.

ERCP: endoscopic retrograde cholangiopancreatography

Figure 5. Histopathology study: Low power photomicrograph of the ampulla with nests of a well differentiated neuroendocrine tumor subjacent to Brunner's glands (Hematoxylin and Eosin stain, 40X original magnification).

Figure 6. High-power photomicrograph showing the stippled chromatin and ample cytoplasm typical of a well-differentiated neuroendocrine tumor (Hematoxylin and Eosin stain, 600X original magnification).

Figure 7. Immunohistochemical stain for synaptophysin showing strong cytoplasmic immunoreactivity within cells of the well-differentiated neuroendocrine tumor (Synaptophysin stain, 40X original magnification).

Figure 8. CT abdomen and pelvis w/contrast: There is a diffuse mass-like enlargement of the mid-body of the pancreas with 3 cm lobular mass projected from the superior and inferior aspects of the pancreas. Findings are highly suspicious for pancreatic neoplasm.

Figure 9. Octreoscan: Blue pointed arrowheads show marked increase uptake within the diffusely enlarged pancreas and pancreatic mass compatible with neuroendocrine tumor. Short white arrows show increased uptake in the right kidney and spleen which are normal findings in the octreoscan.

Figure 10. Octreoscan showing metastatic hepatic lesions: Blue arrowheads show increased uptake lesions in the lateral segment of the left lobe of the liver with another lesion in the right lobe compatible with metastasis. Short white arrow shows increased uptake in the spleen which is a normal finding.