Pathology of Pancreatic Neuroendocrine Tumors

Abstract

Pancreatic neuroendocrine neoplasms have long fascinated clinicians and pathologists, because tumors with similar histopathological appearance can present with distinct clinical syndromes caused by the release of endocrine hormones into the central circulation. In the past these neoplasms have been classified based on their clinical functional status of hormone secretory or nonsecretory. However, with the availability of long-term patient survival data (SEERS database), it is now unequivocally demonstrated that an accurate estimate of a patient’s length of survival is determined by the grade and stage of the tumor and not its functional status. This is reflected in the current grading and staging systems as proposed by the WHO classification of neuroendocrine neoplasms of the pancreas, the European Neuroendocrine Tumour Society TNM classification of GEP-NEN (ENETS 2007), and the US TNM classification tumors (AJCC 2010). Accordingly, the pathological evaluation of pancreatic neuroendocrine neoplasms is focused on grade and stage, while functional status should only be supplemented if a clinical syndrome is recognized.