Increased needle passes for comparable diagnostic yield in endoscopic ultrasound-guided tissue acquisition for pancreatic stiff lesions measured by elastography

Background/objectives: Pancreatic cancer is characterized by tissue stiffness due to the high concentration of cancer-associated fibroblasts and extracellular matrix. Endoscopic ultrasound-guided tissue acquisition (EUS-TA) is performed to diagnose pancreatic cancer but yields false-negative results attributed to inadequate specimens. EUS-elastography is a real-time assessment method to pancreatic tissue stiffness. This study aims to investigate the correlation between diagnostic yield and the number of needle passes based on the stiffness measured by elastography. Methods: Patients who underwent EUS-TA for pancreatic solid mass were retrospectively reviewed and included in this study. The number of needle passes during EUS-TA was determined based on macroscopic on-site evaluation. Tissue stiffness measurements were taken using EUS-elastography. The primary study outcome was the diagnostic yield. The secondary outcome included the number of needle passes required for a diagnosis. Results: A total of 652 patients were included. The average stiffness differed depending on the location of the tumor, and high-stiffness group had more malignant lesions. Although the diagnostic yield was not significantly different between groups, the number of needle passes was significantly higher in the high- stiffness group (3.6 +/- 1.0 vs. 3.2 +/- 0.9, p < 0.001). Conclusions: The higher the stiffness of the pancreatic mass in EUS-elastography, the more needle passes are required to achieve a comparable diagnostic yield.