Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (PNETs) are a heterogeneous group of tumors with significant differences in genetics, clinical presentation, imaging features, and biological behavior. PNETs are thought to arise from common precursor neuroendocrine cells, whose embryologic origin remains controversial. The incidence and prevalence of PNETs is steadily increasing because of improved diagnosis of early-stage disease and improved survival. PNETs have the ability to induce clinical syndromes secondary to secretion of functional hormones. These tumors can be divided into functional and nonfunctional tumors, based on whether they are associated with such clinical syndromes. The World health Organization categorizes PNETS in two major groups: well-differentiated PNETs and poorly-differentiated neuroendocrine carcinomas. Well-differentiated tumors are further subdivided into low-grade (G1), intermediate-grade (G2), and high-grade (G3) tumors. This chapter discusses well-differentiated PNETs such as insulinomas, gastrinomas, vasoactive intestinal polypeptidomas, glucagonomas, and nonfunctional PNETs.