Preoperative diagnosis of nonfunctioning pancreatic neuroendocrine tumors.

The aim of this study is to summarize the experience of preoperative diagnosis for nonfunctioning pancreatic neuroendocrine tumors (NFPNETs). The medical records of patients with NFPNETs were identified from 2001 to 2009 in a single center. They were all reviewed and analyzed for their demographics, clinical presentation, preoperative laboratory evaluation and radiographic characterization. Twenty-six patients (11 men and 15 women) in the past 8 years were diagnosed with NFPNETs. Almost all patients had the normal level of exocrine tumor markers. Although it was not difficult to find tumors by traditional imaging modalities including CT and MRI, the misdiagnosis rate was as high as 81.2%. Perfusion CT was helpful to predict the biological behavior of tumors and even identified NFPNETs as benign or malignant. The preoperative diagnosis for NFPNETs can be confirmed by one or the combination of CgA, perfusion CT, FNA-EUS, PET and octreoscans. NFPNETs should be aroused suspicion of normal exocrine tumor markers and relative specific imaging appearance, which can be proved by one or the combination of CgA, perfusion CT, FNA-EUS, PET and octreoscans.