EUS-guided FNA in the diagnosis of pancreatic neuroendocrine tumors before surgery

Abstract

The use of EUS for precise preoperative evaluation of pancreatic neuroendocrine tumors is well established; up to 80% of insulinomas can be localized. However, the EUS appearance of pancreatic neuroendocrine tumors can be similar to that of benign peripancreatic lymph nodes. The aim of this study was to evaluate the role of EUS-guided FNA in this setting. Thirty patients (18 women, 12 men) with 33 pancreatic/peripancreatic lesions confirmed by surgery underwent EUS-guided FNA between February 1997 and September 2002. Transabdominal US and CT were obtained in all patients before EUS. The diagnosis of pancreatic neuroendocrine tumor was established based on morphologic appearance and immunohistochemical staining of cytologic and surgical specimens. EUS detected 32 of the 33 (96.9%) lesions (mean diameter 20 mm, range 5-97 mm). There was one complication (abdominal pain). For the 30 patients, the following diagnoses were made: functioning pancreatic neuroendocrine tumor (16 patients), non-functioning pancreatic neuroendocrine tumor (7), peripancreatic lymph node (5), inflammatory intrapancreatic nodule (1), and peripancreatic splenosis (1). Sensitivity, specificity, positive and negative predictive values, and accuracy of EUS-guided FNA were 82.6%, 85.7%, 95%, 60%, and 83.3%, respectively. There was one false-positive diagnosis by EUS-guided FNA and 4 false-negative diagnoses. In two of the latter cases, EUS-guided FNA was unsuccessful. EUS-guided FNA is accurate and safe for the diagnosis of pancreatic neuroendocrine tumor and may have a role in determining management strategy.