Comparative Diagnostic Accuracy of EUS-Guided Fine-Needle Biopsy Versus Aspiration for Pancreatic Serous Cystic Neoplasms: A Retrospective Cohort Study

<b>Background:</b> Serous cystic neoplasm (SCN) is a common benign pancreatic lesion frequently encountered in practice. However, diagnostic confirmation by Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) is often limited by inadequate tissue acquisition. Fine-needle biopsy (FNB) has been increasingly performed. We aimed to compare the diagnostic yield of SCN using FNB and FNA needles and to identify factors associated with successful diagnosis. <b>Methods</b>: We retrospectively analyzed 77 patients with pancreatic lesions suspected to be SCN who underwent either EUS-FNB (<i>n</i> = 47 procedures) or EUS-FNA (<i>n</i> = 50 procedures). The primary outcome was diagnostic yield. Secondary outcomes included predictors of diagnostic yield, which were evaluated using univariate and multivariate logistic regression analyses. Receiver operating characteristic (ROC) analyses were performed to identify the optimal biopsy strategy. <b>Results</b>: Diagnostic yield was significantly higher with EUS-FNB than with EUS-FNA (44.68% vs. 14.00%; OR 4.96, 95% CI 1.85-13.28, <i>p</i> < 0.01). From univariate and multivariate analysis, larger cyst size, use of the Franseen FNB needle, and a higher number of needle passes were independent factors associated with diagnostic yield. ROC analysis showed modest discrimination for cyst size (AUC 0.69), with an optimal cutoff of ≥17 mm (sensitivity 87.50%, specificity 41.51%). <b>Conclusions</b>: EUS-FNB provided superior diagnostic yield compared with EUS-FNA for pancreatic SCN. Lesion size, use of a Franseen needle, and the number of needle passes are key factors associated with successful tissue diagnosis.