The goal of this prospective observational study is to generate new personalised 3D preclinical models of pancreatic neuroendocrine tumors. The models will be exploited for studying the mechanisms underlying disease development and progression, as well as for performing drug testing. For the development of the newly proposed models, patients' surgical specimens will be evaluated by the Pathological Unit. If the presence of pathological material in excess, not required for the routine diagnostic procedure, is confirmed, such material will be employed for the generation of the proposed personalised models.