[Gastroenteropancreatic neuroendocrine tumors: what must the pathologist know and do in 2014?]

The diagnostic management of a possible case of gastroenteropancreatic neuroendocrine tumor has much changed in the last 10 years. It is now made of four successive steps. The first step is the positive diagnosis, i.e. the definitive identification of the neuroendocrine nature of the tumor: it relies on morphological and immunohistochemical arguments; several national and international recommendations have now clarified the immunohistochemical arguments necessary for, and sufficient to make a diagnosis of gastroenteropancreatic neuroendocrine tumor. The second step is the determination of the grade, essential for the evaluation of the risk of progression: it relies on the determination of the proliferative capacities, according to the proposals of the European NeuroEndocrine Tumor Society (ENETS), later adopted by WHO in 2010. The third step is the histoprognostic classification, which must use a standardized terminology: it is required to use the specific classification proposed in 2010 by WHO in the framework of the revision of the classifications of digestive tumors. The last step is staging, which relies on the use of one of the existing TNM classifications, that, official, proposed by UICC/AJCC or that proposed by ENETS. The minimal informations, which must be present in the pathological report have been stated by the Société Française de Pathologie, at the request of the French National Cancer Institute.