ABSTRACT
Pancreatic endocrine tumors can be broadly classified as functional or non-functional. Despite changing trends, the majority of clinically relevant pancreatic endocrine tumors are functional ( 3 ). The proportion of non-functioning tumors, in series of islet cell neoplasms, has varied over time, ranging between 15% and 53% of cases ( 4-7 ). While the definition of non-functional has been inconsistent in many reports, increased use of more sophisticated imaging modalities has allowed clinically silent intra-abdominal masses to be identified incidentally and many series report an increased incidence of non-functioning neoplasms ( 8 , 9 ). Overall, the reported 35% to 50% incidence of non-functioning endocrine tumors suggest that non-functional tumors are at least as common as insulinomas and more common than all of the remaining pancreatic endocrine tumor types ( 2 ).
