Pre-operative Diagnosis of Pancreatic Neuroendocrine Tumors with Endoscopic Ultrasonography and Computed Tomography in a Large Series

Background & Aims: Diagnosis of pancreatic neuroendocrine tumors (p-NETs) is frequently challenging. We describe a large series of patients with p-NETs in whom both pre-operative Computed Tomography (CT) and Endoscopic Ultrasonography (EUS) were performed. Methods: This was a retrospective analysis of prospectively collected sporadic p-NET cases. All patients underwent both standard multidetector CT study and EUS with fine-needle aspiration (FNA). The final histological diagnosis was achieved on a post-surgical specimen. Chromogranin A (CgA) levels were measured. Results: A total of 80 patients (mean age: 58 +/- 14.2 years; males: 42) were enrolled. The diameter of functioning was significantly lower than that of non-functioning p-NETs (11.2 +/- 8.5 mm vs 19.8 +/- 12.2 mm; P = 0.0004). The CgA levels were more frequently elevated in non-functioning than functioning pNET patients (71.4% vs 46.9%; P = 0.049). Overall, the CT study detected the lesion in 51 (63.7%) cases, being negative in 26 (68.4%) patients with a tumor <= 10 mm, and in a further 3 (15%) cases with a tumor diameter <= 20 mm. CT overlooked the pancreatic lesion more frequently in patients with functioning than non-functioning p-NETs (46.5% vs 24.3%; P = 0.002). EUS allowed a more precise pre-operative tumor measurement, with an overall incorrect dimension in only 9 (11.2%) patients. Of note, the EUS-guided FNA suspected the neuroendocrine nature of tumor in all cases. Conclusions: Data of this large case series would suggest that the EUS should be included in the diagnostic work-up in all patients with a suspected p-NET, even when the CT study was negative for a primary lesion in the pancreas.