Can the wet suction technique change the efficacy of endoscopic ultrasound-guided fine-needle aspiration for diagnosing autoimmune pancreatitis type 1? A prospective single-arm study.

Abstract

Other than surgery, endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is the only procedure for histologically diagnosing autoimmune pancreatitis (AIP). However, adequate specimens are difficult to obtain. Recently, more adequate specimens were reported to be obtained with EUS-FNA with a wet suction technique (WEST) than with conventional EUS-FNA. To histologically diagnose AIP by EUS-FNA with a WEST. Eleven patients with possible type 1 AIP between February 2016 and August 2018 underwent EUS-FNA with a WEST (WEST group), with four punctures by 19 or 22 G needles. As a historical control, 23 type 1 AIP patients who underwent no fewer than four punctures with 19 or 22 G needles were enrolled (DRY group). Patient characteristics and histological findings were compared between the two groups. Three histopathological factors according to the International Consensus Diagnostic Criteria were significantly greater in the WEST group than the DRY group [lymphoplasmacytic infiltrate without granulocytic infiltration: 9 (81.8%) vs 6 (26.1%), P = 0.003, storiform fibrosis: 5 (45.5%) vs 1 (4.3%), P = 0.008, abundant (> 10 cells/HPF) IgG4-positive cells: 7 (63.6%) vs 5 (21.7%), P = 0.026]. Level 1 or level 2 histopathological findings were observed more often in the WEST group than in the DRY group [8 (72.7%) vs 3 (13.0%), P = 0.001]. EUS-FNA with a WEST was more successful than standard EUS-FNA in histologically diagnosing AIP.