Pancreatic Neuroendocrine Tumors in the 21 st Century—An Update

Pancreatic neuroendocrine tumors (PNETs) are rare, reported to account for less than 1% - 2% of all pancreatic tumors. This, however, is likely an underestimation, as improved radiologic techniques and heightened awareness have resulted in an increase in the detection of incidentalomas, with estimations of true prevalence as high as 10%. The term “PNET” is an umbrella name that encompasses a heterogeneous group of neoplasms each with distinct clinical presentations, diagnostic radiographic features, management principles, and tumor/patient outcomes. In this context, accurate diagnosis is challenging, and management guidelines remain unclear. A high degree of clinical suspicion is required for best patient management. This manuscript provides an update on PNETs in the 21st century, in which we re-examine the terminology, epidemiology, classification, etiopathogenesis, radiographic and histopathologic diagnostic features, management for localized and metastatic disease, as well as a review of features defining functional and non-functional PNETS, and finally deliberates on the prognosis and predictive features of this unpredictable and largely unfathomable neoplasm.