Endoscopic Ultrasound (EUS)-guided Fine Needle Aspiration (FNA) Accurately Diagnoses Smaller Pancreatic Neuroendocrine Tumors Compared to Computerized Tomography (CT)-guided FNA

Background: The role of EUS-guided FNA as a highly sensitive modality in the diagnosis of pancreatic adenocarcinoma is well documented. However, there is very little published data on the role of EUS-FNA in the diagnosis or management of pancreatic neuroendocrine tumors (NETs). The aim of the current study is to compare the sensitivity of EUS-FNA with that of CT-FNA in the diagnosis of pancreatic NETs.

Methods: This is a single institution analysis of the operating characteristics of EUS-FNA and CT-FNA in detecting pancreatic NETs. Patients diagnosed with a pancreatic NET-determined by FNA cytology, surgical pathology, or a history of multiple endocrine neoplasia (MEN)-and who underwent EUS-FNA or CT-FNA-were selected for this study. Procedure related data, including tumor size and location, presence of a cytotechnologist, and number of FNA passes were recorded. The result of each FNA was compared to the final clinico-pathological diagnosis to calculate sensitivity.

Results: A total of 26 FNA cases (16 by EUS, 10 by CT) from 25 patients were reviewed. Four patients had MEN-1. NETs diagnosed by EUS-FNA were smaller compared with CT-FNA (2.9±1.0 vs. 6.5±1.9cm, p=0.006) and were more likely to be located in the head (56% vs. 10%, p=0.009). There was no significant difference in sensitivity between EUS-FNA and CT-FNA specimens (68.8% vs. 88.9%, p=0.23). Unlike CT-FNA, a cytotechnologist was not routinely present during EUS-FNA.

Conclusions: EUS-guided FNA is as sensitive as CT-guided FNA in diagnosing pancreatic NETs, but its main advantage may lie in its ability to accurately diagnose smaller NETs located in the head of the pancreas. The presence of a cytotechnologist may improve the diagnostic sensitivity of EUS-FNA for pancreatic NETs.