Table 3.

Summary of different types of duodenal neuroendocrine tumors

	Gastrinomas	Somatostatinoma	Gangliocytic paraganglioma	Non-functioning d-NETs	Duodenal NECs
Location	Proximal duodenum. > 80% gastrinoma triangle	Ampullary or peri-ampullary region	Peri-ampullary region	Proximal duodenum	Peri-ampullary region
Presenting symptoms	Chronic diarrhea, recurrent and refractory peptic ulcer disease, gastroesophageal reflux disease	Nausea, abdominal pain, weight loss, obstructive jaundice or very rarely somatostatinoma syndrome	Asymptomatic, gastrointestinal bleeding, anemia, abdominal pain	Asymptomatic or nausea, vomiting	Asymptomatic, nausea, vomiting, gastrointestinal bleeding
Diagnosis	BAO/MAO > 0.6, positive Secretin suppression test, EUS, somatostatin receptor scintigraphy (SRS), CT, MRI, selective angiography, Indium 111-labeled diethylenetriamine penta-acetic acid (DTPA) octreotide and (68)Ga-DOTATE PET/CT scan	CT, MRI, endoscopy, EUS-FNA	Endoscopy, EUS-FNA, CT	Endoscopy, EUS-FNA	Endoscopy, EUS-FNA
Treatment	Surgical resection or enucleation of the tumor without pancreaticoduodenectomy for nonmetastatic duodenal gastrinoma. In patients with duodenal gastrinoma with hepatic metastasis treatment options include hormonal therapy with octreotide, chemotherapy (streptozocin, doxorubicin, 5- fluorouracil), radiotherapy with yttrium 90-DOTA-lanreotide, hepatic embolization alone or with chemoembolization, cytoreductive surgery and liver transplantation	Endoscopic resection should be adequate if the NET is less than 1 cm. Transduodenal excision should be done for 1-2 cm tumor. But Whipple’s surgery with local lymph node resection should be considered for more than 2 cm tumor	Endoscopic resection or radical excision including pancreaticoduodenectomy depending on the size, depth of invasion and lymph node metastasis	Transduodenal resection is indicated for d-NETs invading the muscularis propria. Radial surgery is advocated for d-NETs > 2 cm in diameter, d-NETs with lymph nodes involvement and all peri-ampullary d-NETs	radical surgery or chemotherapy

BAO: Basal acid output; MAO: Maximal acid output; (68)Ga-DOTATE PET/CT scan: Gallium -68 DOTATE positron emission tomography/computerized tomography scan; d-NETs: Duodenal neuroendocrine tumors; CT: Computerized tomography; MRI: Magnetic resonance imaging; EUS: Endoscopic ultrasonography; FNA: Fine needle aspiration.