Is pancreatic core biopsy sufficient to diagnose autoimmune chronic pancreatitis?

Objectives: This study aimed to evaluate the adequacy of pancreatic core biopsy in histological diagnosis of autoimmune chronic pancreatitis (AIP).

Methods: 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.

Results: 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.

Conclusions: 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.