The incidence of duodenal neuroendocrine neoplasms has risen over the past decades due to the wide availability and expertise on endoscopy. Although it is thought that tumour size greater than 10 mm, higher tumour grade, and / or location in relation to the ampulla of Vater represent the main risk factors for local or distant metastases, we describe 2 cases of well differentiated grade 1 and grade 2 neuroendocrine tumours, which were measuring less than 10mm at the time of diagnosis, but had an aggressive course during follow up. Furthermore, this article also summarises the available therapeutic strategies for the management of small, low grade, non-functioning, non-ampullary duodenal neuroendocrine neoplasms.