Is Pancreatic Core Biopsy Sufficient to Diagnose Autoimmune Chronic Pancreatitis?

Abstract
This study aimed to evaluate the adequacy of pancreatic core biopsy in histological diagnosis of autoimmune chronic pancreatitis (AIP). Histopathologic study as well as immunohistochemical staining using anti-IgG4 antibody was done with pancreatic tissue specimens of 26 AIP patients (19 transabdominal ultrasound (US)-guided core biopsies, 3 intraoperative wedge biopsies, and 4 surgical resections). Eight patients with alcoholic chronic pancreatitis and 10 patients with pancreatic cancer served as controls. Lymphoplasmacytic sclerosing pancreatitis (LPSP) histology was observed in 26% (5/19) of US-guided core biopsy specimens, 33% (1/3) of open biopsy specimens, and all 4 resection specimens in AIP patients. None of the patients in the control group showed the full spectrum of changes of LPSP. Abundant IgG4-positive cells (>10 cells/high-power field) in the pancreas were observed in 21% (4/19) of AIP patients with US-guided core biopsy specimen. Abundant IgG4-positive cells in the pancreas were also observed in 2 of 8 patients with chronic alcoholic pancreatitis and 1 of 10 patients with pancreatic cancer. Transabdominal US-guided pancreatic core biopsy may not provide enough tissue to evaluate characteristic histopathologic features of AIP that include LPSP or abundant IgG4-positive cell infiltration. The LPSP histology may be specific to AIP, but abundant IgG4-positive cells in the pancreas may not.