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

Background: 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.

Aim: To histologically diagnose AIP by EUS-FNA with a WEST.

Methods: 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.

Results: 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].

Conclusion: EUS-FNA with a WEST was more successful than standard EUS-FNA in histologically diagnosing AIP.

Keywords: Autoimmune pancreatitis; Endoscopic ultrasound-guided fine needle aspiration; Wet suction technique.

Figure 1

Target patients in this study and historical controls. The historical controls were 23 autoimmune pancreatitis patients who underwent endoscopic ultrasonography-guided fine-needle aspiration with no fewer than 4 punctures by 19 or 22 G needles. The target subjects in this study underwent endoscopic ultrasonography-guided fine-needle aspiration with a wet suction technique. The historical controls were considered the DRY group. AIP: Autoimmune pancreatitis; WEST: Wet suction technique.

Figure 2

The wet suction technique method of endoscopic ultrasonography-guided fine-needle aspiration. A: After the stylet of the needle was withdrawn, saline solution was injected into the needle; B: A locked suction syringe with 20 mL of negative pressure was set at the edge of the needle; C: The needle was used to puncture the target lesion; D: then, the lock on the syringe was opened. Saline solution flowed into the suction syringe due to the negative pressure.

Figure 3

The features of a patient with autoimmune pancreatitis diagnosed by endoscopic ultrasonography-guided fine-needle aspiration with a wet suction technique. A: The pancreatic tail is swollen with a capsule-like rim sign as observed on abdominal computed tomography; B: Specimen acquired by wet suction technique (WEST) endoscopic ultrasonography-guided fine-needle aspiration (EUS-FNA) (HE × 200): IgG4-positive plasma cells were observed; C: Specimen acquired by WEST EUS-FNA (EM × 200): obliterative phlebitis was observed; D: Specimen acquired by WEST EUS-FNA (HE × 400): fibrosis with a storiform pattern of plasma cells was observed.