S2259 Use of Through-the-Needle Microforceps Biopsies Aids Accurate Diagnosis of Pancreatic Cysts

Introduction: Pancreatic cysts are incidentally detected in up to 45% of imaging studies in older populations. Accurate diagnosis is critical given the malignant potential of certain cyst types. Traditional fine-needle aspiration (FNA) is often limited with inconclusive results in 30-60% of cases. Through-the-needle microforceps biopsies (TNMB) under endoscopic ultrasound (EUS) guidance enable direct sampling of cyst wall tissue, potentially improving histological diagnosis. This study evaluates the safety, technical success, and diagnostic effectiveness of TNMB compared to FNA in managing pancreatic cysts. Methods: This retrospective study evaluated patients at an American tertiary academic medical center who underwent TNMB and FNA for pancreatic cyst assessment. Primary endpoints were the incidence of discordance between TNMB and FNA results and subsequent changes in diagnosis or management. Secondary endpoints included technical success (completion of TNMB and FNA), clinical success (obtaining a diagnostic sample), and 90-day complication rates. Categorical variables were analyzed using chi-square tests, and continuous variables with t-tests, with significance set at P < 0.05. Results: Twenty-nine patients (65.5% woman, mean age 67.6 ± 11.2 years) underwent TNMB, with 27 also undergoing FNA of pancreatic cysts (mean size, 40.0 ± 18.3 mm). TNMB findings differed from FNA in 14 of 27 cases (51.9%), resulting in changes to diagnosis and management. Six patients underwent surgical resection, with pathology confirming TNMB findings in 100% of cases. Technical success was achieved in 100% of both TNMB and FNA procedures. Clinical success was significantly higher with TNMB (23/29, 79.3%) than with FNA (13/27, 48.1%; P = 0.01). TNMB identified 19 mucinous cysts, including 10 intraductal papillary mucinous neoplasms, 4 mucinous cystic neoplasms, 2 pseudocysts and 2 benign cysts. Three complications requiring hospitalization were observed in the TNMB group. Conclusion: This study is among the largest single-center North American analyses of TNMB and demonstrates its effectiveness in accurately diagnosing pancreatic cysts and improving diagnostic yield compared to traditional FNA. Furthermore, TNMB is a relatively safe procedure with a high clinical success rate. With the increasing incidence of incidentally detected pancreatic cysts, TNMB may serve as a valuable tool for distinguishing high-risk lesions requiring close monitoring or surgical intervention from low-risk lesions that can be safely observed.