Duodenal neuroendocrine neoplasms: a still poorly recognized clinical entity

Background: Duodenal neuroendocrine neoplasms (dNENs) are rare tumors, which usually show good prognosis. The optimal management of these tumors is still far from being clearly understood because of their rarity and the poor level of knowledge about their natural history. Herein, we have reviewed the literature on dNENs to collect and analyze the current data on epidemiology, diagnosis and management of these rare tumors. Methods: Bibliographical searches were performed in PubMed, using the following keywords: duodenal neuroendocrine neoplasm; duodenum; gastrinoma; diagnosis; therapy; guidelines. We searched for all relevant articles published over the last 15 years. Non-English language papers were excluded. Results: We reviewed the pertinent articles about dNENs. Upper gastrointestinal endoscopy with biopsy is the cornerstone of the dNENs diagnostic process. Endoscopic ultrasound with fine-needle aspiration/biopsy should be performed in order to locally stage the disease and in all cases of non-diagnostic endoscopy. Endoscopic or complete surgical removal of the primary lesion is the recommended treatment and is generally achievable for the majority of the patients. A less aggressive approach may be suggested for well-differentiated low-stage tumors. After NEN removal, patients should be closely followed-up especially during the first 3 years by endoscopic examination, imaging tests and CgA measurements. Conclusions: The multi-disciplinary approach and the preservation of the quality of life of the patients play a key role in the therapeutic process for dNENs. Further studies are needed to better define standardized guidelines specific to dNENs, including optimal management approaches and follow-up intervals.