Performance characteristic of endoscopic ultrasound-guided fine needle aspiration is unaffected by pancreatic mass size

Background and study aims: Despite a well-established tool for diagnosis of pancreatic masses, endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) studies have shown suboptimal diagnostic performance at divergent mass sizes. Since the impact of gold standard follow-up and presence of on-site evaluation on this observation is unknown, we aimed to study the performance characteristics of EUS-FNA under these strict conditions. Patients and methods: EUS-FNA results from pancreatic mass lesions performed between July 2000 and March 2013 were evaluated. All patients with histological follow-up were then stratified into four groups: Group A (10mm), Group B (11-20mm), Group C (21-40mm), and Group D (>40mm). Sensitivity and diagnostic accuracy were calculated for each group and compared. Results: A total of 612/3832 (16%) patients with pancreatic masses who underwent EUS-FNA had histology confirmation. Of these, 81 were excluded due to unavailable lesion size, while the rest formed the study cohort. Mean age (SD) was 65.8 years (9.3) with 51.2% female. The mean number of passes for the entire cohort was 2.9 (SD 1.9; range 1-12); patients in group D had a significantly higher number of passes for on-site diagnosis (P=0.0124). There was no significant difference between the groups for sensitivity (P=0.1134) or diagnostic accuracy (P=0.2111). Proportional trend analysis revealed no significant correlation between size and sensitivity (P=0.6192). The size of lesion measured by EUS was not associated with sensitivity or specificity after adjusting for age, sex, and pancreatic location. Conclusion: In the presence of rapid on-site cytopathology and when final histology is taken as the gold standard, pancreatic mass size does not affect the performance characteristics of EUS-FNA.