Pathological Evaluation and Classification of Digestive Neuroendocrine Neoplasms

The pathological diagnosis of digestive neuroendocrine neoplasms (NENs) has been modified since 2010, with successive World Health Organization (WHO) classifications, with the last ones published in 2019 for digestive NENs and in 2022 for all locations. New immunohistochemical markers are emerging in addition to morphology to help eliminate differential diagnosis and to better classify and characterize prognosis and select the best treatments for patients. In the digestive system, the tumor, node, metastasis (TNM) classification has been deemed specific for neuroendocrine tumors since the publication of the eighth edition of the American Joint Cancer Committee/International Union Against Cancer (AJCC/UICC), with specificities according to the different locations.