Gastro-intestinal endocrine tumors: morphological and clinicopathological characteristics

Gastro-intestinal endocrine tumors constitute a heterogeneous group of tumors. Their clinical features, functional properties, and clinical course differ according to their site of origin. From a practical point of view, several topographical groups may be distinguished: (a) stomach, (b) duodenum and proximal jejunum, (c) ileum and caecum, (d) appendix, (a) colon and rectum. In each of these groups, a certain degree of tumor heterogeneity persists, especially between colon and rectal tumors, which would be better considered apart. In this review, we will describe the main functional, morphological and evolutive features of endocrine tumors in each of the topographical groups currently recognized.