Diagnostic differentiation of pancreatic neuroendocrine tumor from other neoplastic solid pancreatic lesions during endoscopic ultrasound-guided fine-needle aspiration

Objectives: To identify factors differentiating pancreatic neuroendocrine tumors (PNETs) from non-PNET neoplastic solid pancreatic lesions (SPLs) and assess the accuracy of endoscopic ultrasound-guided fineneedle aspiration (EUS-FNA). Methods: This is a retrospective study at a tertiary center of consecutive patients referred for EUS from2004 to 2011. Themain outcomeswere pretest predictors and accuracy of EUS-FNA for diagnosis of PNET. Results: Among a total of 1108 EUS-FNAs for pancreatic lesions, 672 patients (PNET = 91, non-PNET neoplastic-SPLs = 581) had neoplastic-SPLs. The sensitivity, specificity, and accuracy of EUS-FNA for diagnosis of PNETs were 98.9%, 100%, and 99.9%, respectively. The mean needle-passes were 3.0/patient. The EUS volume (mean/year per endosonographer) in preceding 3 years significantly correlated with fewer needle passes (rs: [-0.26]; P = 0.02). Multivariate analysis demonstrated that patients with PNETwhen compared to non-PNET neoplastic-SPLs were younger (odds ratio [OR], 3.23; 95% confidence interval [95% CI], 1.19-9.09; P = 0.001), have 2 or more pancreatic lesions (OR, 5.63; 95% CI, 1.74-18.2; P = 0.005), and lower CA 19-9 values (OR, 10.0; 95% CI, 3.13-33.3; P = 0.001). Further, PNETs were less likely to have weight loss (OR, 0.40; 95% CI, 0.17-0.90; P = 0.03), current smoking (OR, 0.47; 95% CI, 0.22-0.98; P < 0.05), pancreatic ductal dilation (OR, 0.28; 95% CI, 0.13-0.60; P = 0.002), or imaging evidence of arterial invasion (OR, 0.22; 95% CI, 0.07-0.71; P = 0.01). Conclusions: Although pre-FNA findings can reliably characterize, EUS-FNA is highly accurate for the diagnosis of PNETs.