Histological diagnosis of autoimmune pancreatitis using EUS-guided trucut biopsy: a comparison study with EUS-FNA

Purpose The aim of this study was to evaluate the feasibility and safety of endoscopic ultrasonography (EUS)guided trucut biopsy (TCB) for diagnosis of autoimmune pancreatitis (AIP). Methods Fourteen patients with suspected AIP based on imaging studies underwent both EUS-guided fine-needle aspiration (FNA) and EUS-TCB for diagnosis of AIP and exclusion of pancreatic cancer (PC). According to the revised Japanese clinical diagnostic criteria, AIP was diagnosed in eight while the remaining six patients had pancreatitis of other etiologies. Pathologically, AIP was defined as lymphoplasmacytic sclerosing pancreatitis (LPSP), and sub-divided into two types: definite LPSP (d-LPSP) showing fulspectrum of LPSP and probable LPSP (p-LPSP) without obliterative phlebitis or abundant (> 10 cells/ hpf) IgG4-positive plasmacytes infiltration. Results PC was excluded in all patients. EUS-FNA resulted in three of eight patients with AIP were reported as p-LPSP, one was reported as normal, and 4 were inconclusive. One of six with non-autoimmune pancreatitis was diagnosed as p-LPSP on EUS-FNA, one as idiopathic chronic pancreatitis (ICP) and four were inconclusive. By using EUS-TCB, all AIP patients were diagnosed as LPSP (4 d-LPSP and 4 p-LPSP). Of the six patients with non-autoimmune pancreatitis, three were diagnosed as LPSP (1 d-LPSP and 2 p-LPSP) and three showed ICP on TCB. No complications were identified in any patient with either EUS-FNA or TCB. Conclusion EUS-TCB is a safe and accurate procedure for obtaining a histological diagnosis in patients with suspected AIP. EUS-TCB can serve as a rescue technique in cases of AIP lacking typical findings.