Histological diagnosis and grading of pancreatic neuroendocrine tumor by endoscopic ultrasound-guided fine needle biopsy using a 25-gauge needle with a core trap: A multicenter prospective trial

Preoperative grading of pancreatic neuroendocrine tumors (PanNET) is challenging. The aim of this study was to prospectively evaluate the use of a 25-gauge needle with a core trap for diagnosis and grading of PanNET. This multicenter prospective trial was registered with the University Hospital Medical Information Network (UMIN000021409). Consecutive patients with suspected PanNET between June 2016 and November 2017 were enrolled. All patients underwent endoscopic ultrasound-guided fine needle biopsy (EUS-FNB) using a 25-gauge needle with a core trap. Samples obtained after the first needle pass were used for central pathological review. EUS-FNB was evaluated in terms of (i) technical success rate, (ii) adequacy for histological evaluation, (iii) complication rate during the procedure, and (iv) concordance between PanNET grading on EUS-FNB and that after analysis of the resected tumor. Fifty-two patients were enrolled. Of the 36/52 patients who underwent surgical resection, 31 were finally diagnosed with PanNET and were eligible for analysis. The technical success rate of EUS-FNB was 100%. The rate of adequacy for histological evaluation was 90.3%. There were no complications related to EUS-FNB. The concordance rate between PanNET grading on EUS-FNB and that after analysis of the resected tumor was 82.6% (95% confidence interval = 61.22–95.05, P = 0.579). EUS-FNB using a 25-gauge needle with a core trap is feasible, providing histological samples are of sufficient quality for diagnosis and grading of PanNET.