Classification et facteurs pronostiques des tumeurs neuroendocrines intestinales

Intestinal neuroendocrine tumours (NETs) are the most frequent of digestive NETs. The diagnosis of it relies on both histological and immunohistochemical arguments. In 2010, the WHO classified the intestinal NETs based on two criterias: morphological differentiation and histological grade. Four categories were recognised: two for well-differentiated tumours, G1 and G2, one for neuroendocrine carcinomas, poorly differentiated, and one for the mixed tumours. The WHO classification of pancreatic NETs has been revised in 2017 and this revision would probably be applied also to intestinal NETs. The main modification is the introduction of a third category of well-differentiated tumours, NET G3. The histoprognostic factors in intestinal NETs remain morphological and no molecular biomarker has been validated yet. The most interesting molecular data are for large cell neuroendocrine carcinomas, which may display the same molecular signatures than conventional adenocarcinomas, such as the MSI phenotype. The next classification will have to integrate this new information.