title: Classification and pathology of gastroenteropancreatic neuroendocrine neoplasms.
abstract: Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are composed of cells with a neuroendocrine phenotype. The old and the new WHO classifications distinguish between well-differentiated and poorly differentiated neoplasms. All well-differentiated neoplasms, regardless of whether they behave benignly or develop metastases, will be called neuroendocrine tumours (NETs), and graded G1 (Ki67 <2%) or G2 (Ki67 2-20%). All poorly differentiated neoplasms will be termed neuroendocrine carcinomas (NECs) and graded G3 (Ki67 >20%). To stratify the GEP-NETs and GEP-NECs regarding their prognosis, they are now further classified according to TNM-stage systems that were recently proposed by the European Neuroendocrine Tumour Society (ENETS) and the AJCC/UICC. In the light of these criteria the pathology and biology of the various NETs and NECs of the gastrointestinal tract (including the oesophagus) and the pancreas are reviewed.
authors: Department of Pathology, Technical University of München, Ismaninger Strasse 22, 81675 München, Germany. guenter.kloeppel@alumni.uni-kiel.de
authors: Günter
authors: G
authors: Klöppel
mesh_terms: D005770:Gastrointestinal Neoplasms / Q000145:classification* / Q000473:pathology / Q000628:therapy; D006801:Humans; D018358:Neuroendocrine Tumors / Q000145:classification* / Q000473:pathology / Q000628:therapy; D010190:Pancreatic Neoplasms / Q000145:classification* / Q000473:pathology / Q000628:therapy; D014944:World Health Organization