Background Pancreatic cystic lesions (PCLs) are increasingly found on cross-sectional imaging, with the majority having a low risk for malignancy. The added value of fine-needle aspiration (FNA) in risk stratification remains unclear. We evaluated the impact of three FNA needles on diagnostic accuracy, clinical management, and the ability to accrue fluid for tumor markers. Methods A multicenter prospective trial randomized 250 patients with PCLs≥13mm 2:1:1 to 19G Flex, 19G, and 22G needles with crossover for repeated FNA procedures. Diagnostic accuracy was established at 2-year follow-up, with the final diagnosis from surgical histopathology or consensus diagnosis by experts based sequentially on clinical presentation, imaging, and aspirate analysis in blinded review. Results Enrolled patients (36% symptomatic) had PCLs in the head (44%), body (28%), and tail (26%). Percentage of cyst volume aspirated was 78% (72%-84%) for 19G Flex, 74% (64%-84%) for 22G, and 73% (63%-83%) for 19G (P =0.84). Successful FNA was significantly higher for 19G Flex (89% [82%-94%]) and 22G (82% [70%-90%]) compared with 19G (75% [63%-85%]) (P =0.02). Repeated FNA was required more frequently in head/uncinate lesions than in body and tail (P <0.01). Diagnostic accuracy of the cyst aspirate was 84% (73%-91%) against histopathology at 2-year follow-up (n=79), and 77% (70%-83%) against consensus diagnosis among nonsurgical cases (n=171). Related serious adverse events occurred in 1.2% (0.2%-3.5%) of patients. Conclusions Our study results demonstrate a statistically significant difference among the three needles in the overall success rate for aspiration, but not in the percentage of cyst volume aspirated. Flexible needles may be particularly valuable in sampling cystic PCLs in the pancreatic head/uncinate process.
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