Effect of Pancreatic Mass Size on Clinical Outcomes of Endoscopic Ultrasound-Guided Fine-Needle Aspiration.

Background: Endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) has high diagnostic accuracy for pancreatic diseases. However, the effect of mass size on diagnostic accuracy has yet to be determined, especially for small pancreatic lesions. We aimed to determine the effect of pancreatic mass size on the diagnostic yield of EUS-FNA.

Methods: We searched the database in Hokkaido University Hospital between May 2008 and December 2016 and identified solid pancreatic lesions examined by EUS-FNA. All lesions were stratified into five groups based on mass sizes: groups A (< 10 mm), B (10-20 mm), C (20-30 mm), D (30-40 mm) and E (≥ 40 mm). The sensitivity, specificity, diagnostic accuracy and adverse event rate were retrospectively evaluated.

Results: We analyzed a total of 788 solid pancreatic lesions in 761 patients. The patients included 440 males (57.8%) with a mean age of 65.7 years. The sensitivities in groups A (n = 36), B (n = 223), C (n = 304), D (n = 147) and E (n = 78) were 89.3%, 95.0%, 97.4%, 98.5% and 98.7%, respectively, and they significantly increased as the mass size increased (P < 0.01, chi-squared test for trend). The diagnostic accuracies were 91.7%, 96.4%, 97.7%, 98.6% and 98.7%, respectively, and they also significantly increased as the mass size increased (P = 0.03). Multivariate analysis showed that pancreatic mass size was associated with diagnostic accuracy. The adverse event rates were not significantly different among the five groups.

Conclusions: The sensitivities and diagnostic accuracies of EUS-FNA for solid pancreatic lesions are higher for lesions ≥ 10 mm in size, and they are strongly correlated with mass size.