Duodenal NETs (duodenal carcinoids)

Duodenal neuroendocrine tumors (NETs; divided in type 1-5) are more rare than duodenal adenomas or adenomcarcinomas, and includes duodenal gastrinomas, somatostatinomas and gangliocytic paraganglioma. A short overview follows.

Gastrinomas – Type 1 duodenal NETs
Type 1 duodenal NET is the most common (40%), which is a gastrin-producing, submucous tumor (gastrinoma) leading to the Zollinger-Ellison syndrome (ZES). Serum gastrin and chromogranin A are raised, and the patients often have severe abdominal symptoms with dyspepsia, recurrent ulcerations in absence of Helicobacter Pylori and diarrhea. Before surgical treatment it is important to examine possible association with multiple endocrine neoplasia type 1 (MEN-1) to plan the proper treatment. The treatment is surgical, by local resection or rarely pancreaticodudenectomy. Sporadic gastrinomas metastasize more often than those associated with MEN-1. In some cases with MEN-1 and ZES long-term treatment with proton pump inhibitors (PPI) may be an alternative.

Gastric NETs (gastric carcinoids)

Somatostatinomas – Type 2 duodenal NETs
About 15-30% express somatostatin, but are clinically non-functioning. They are usually located in the papilla of Vater as 1-2 cm nodules, and lymph node and liver metastases are presented in about 50%. A third are associated with neurofibromatosis type 1, NF1 (von Recklinghausen’s neurofibromatosis) and occasionally with pheochromocytoma, which should be ruled out preoperatively. Surgical treatment may be local excision or pancreatico-duodneotomy.

Type 3- and 4 duodenal NETs
These are rare tumors. Type 3 are denoted ganlgiocytic paragangliomas and type 4 may express and release serotonin, calcitonin or pancreatic polypeptide (PP). The tumors are usually small with a low Ki67 index.

Type 5 duodenal NET – Duodenal PDEC.
Is a highly uncommon tumor, and should be treated as other PDECs (poorly differentiated neuroendocrine carcinoma).