Features of chronic pancreatitis by endoscopic ultrasound influence the diagnostic accuracy of endoscopic ultrasound‐guided fine‐needle aspiration of small pancreatic lesions

Background and Aim In chronic pancreatitis ( CP ) patients, diagnosis of small pancreatic lesions by endoscopic ultrasound‐guided fine‐needle aspiration ( EUS ‐ FNA ) is challenging. Thus, the aim of the present study was to investigate whether CP influences the diagnostic ability of EUS ‐ FNA for pancreatic lesions ≤10 mm. Methods One hundred and seventeen patients who underwent EUS ‐ FNA for pancreatic lesions ≤10 mm in size were enrolled. Patients were classified into two groups based on features of CP observed by EUS ( EUS ‐ CP features) in accordance with the Rosemont classification. The CP group was defined as cases consistent with CP or suggestive of CP , and the non‐ CP group was defined as cases indeterminate for CP or normal. Factors influencing the diagnostic accuracy of EUS ‐ FNA and CP status in pancreatic tumors were also investigated. Results Diagnostic ability of EUS ‐ FNA (overall cases, non‐ CP vs CP ) had sensitivity (80.4%, 96.7% vs 57.1%; P < 0.001), specificity (100%, 100% vs 100%; P > 0.05), and accuracy (91.5%, 98.6% vs 80.4%; P = 0.001). In multivariate analysis of factors influencing the accuracy of EUS ‐ FNA , CP significantly lowered the accuracy ( P = 0.048; odds ratio [ OR ] = 9.21). Among pancreatic cancer patients, the number of CP patients was significantly higher than the number of patients with benign lesions ( P = 0.023). In multivariate analysis, lobularity without honeycombing was more frequently observed in cases of pancreatic cancer ( P = 0.018; OR , 12.65). Conclusion Endoscopic ultrasound‐guided FNA offers high accuracy for small pancreatic lesions ≤10 mm. However, in cases with CP , the diagnostic ability of EUS ‐ FNA is significantly reduced.