Neuroendokrine Neoplasien

The gastrointestinal tract represents, together with the lung, the most common site for the occurrence of neuroendocrine neoplasms (NEN). NEN include two main groups of entities: the well-differentiated neuroendocrine tumors (NET), which, although all being potentially malignant, usually bear a good prognosis and the poorly differentiated and clinically aggressive neuroendocrine carcinomas (NEC). A third group is represented by neoplasms displaying a neuroendocrine and a nonneuroendocrine differentiation, so-called mixed neuroendocrine and nonneuroendocrine neoplasms (MiNEN). The relative frequency of NET and NEC differs depending on the anatomical location along the esophagus, stomach and intestine, which also affects the spectrum of clinical presentations. The diagnosis of NEN and their classification relies on well-established immunohistochemical markers. The molecular pathogenesis of NEN, which in some cases underlies their biological behavior, is currently being clarified; however, molecular biomarkers for personalized treatment approaches are mostly missing.