Diagnostic and Interventional Role of Endoscopic Ultrasonography for the Management of Pancreatic Neuroendocrine Neoplasms

Abstract

Pancreatic neuroendocrine neoplasms (PanNENs) are relatively rare, but their incidence has increased significantly in the last decades. Precise diagnosis and prognostic stratification are crucial for proper patient management. Endoscopic ultrasound (EUS) is the modality of choice for diagnosis of solid pancreatic tumors, showing a higher tumor detection rate than other imaging modalities, especially for small size lesions. EUS also serves as a guide for preoperative sampling and other interventions. EUS-tissue acquisition is a safe and highly accurate technique for cyto/histological diagnosis of PanNENs with a well-demonstrated correlation between Ki-67 proliferation index values and tumor grading on EUS and surgical specimens according to the WHO 2017 classification. Furthermore, the possibility of a preoperative EUS-guided fine needle tattooing or fiducial markers placement may help the surgeon to locate small and deep tumors, thus avoiding formal pancreatic resections in favor of parenchymal-sparing surgery. Finally, locoregional ablative treatments using either ethanol injection or radiofrequency ablation have been proposed in recent studies with promising results in order to control symptoms or reduce tumor burden in selected patients unfit for surgery with functioning or non-functioning PanNENs. This article review highlights the current role of EUS in PanNENs management, focusing on the present and future applications of EUS-guided interventions.

Keywords: endoscopic ultrasonography (EUS); endoscopic ultrasound guided tattooing; endoscopic ultrasound-guided fiducial placement; endoscopic ultrasound-guided fine needle aspiration (EUS-FNA); ethanol ablation; pancreatic neuroendocrine neoplasms (PanNENs); radiofrequency ablation (RFA).

Figure 1

(A) Endoscopic ultrasound image of a small, well rounded, hypoechoic lesion with regular margin and dilated Wirsung in the head of the pancreas highly suggestive for neuroendocrine tumor. (B) The diagnosis of neuroendocrine tumor was confirmed by tissue specimen gathered using EUS-FNA. MPD, main pancreatic duct; D2, diameter.

Figure 2

Endoscopic ultrasound elastography of a small pancreatic head neuroendocrine tumor. Two different areas (A, B) from the region of interest were selected for quantitative elastographic analysis. Area (A) is a lesion representative area including the biggest possible area of the tumor. Area (B) refers to soft (red) reference tissue outside the tumor. The quotient (B/A) (strain ratio) is considered as the measure of the elastographic evaluation.

Figure 3

Endoscopic ultrasound (EUS) revealed a 10 mm hypoechoic lesion of the pancreas (right panel). Contrast-enhanced EUS showed typical homogeneous hyperenhancement of the lesion during the arterial phase in comparison to the surrounding pancreatic parenchyma (left panel) after intravenous injection of contrast agent (Sonovue™, Bracco Imaging, Milan, Italy). P, power; MI, mechanical index.

Figure 4

A magnified endoscopic ultrasound view demonstrating a fiducial just released inside a small pancreatic lesion.