Is Idiopathic Chronic Pancreatitis an Autoimmune Disease?

Background & Aims: The proportion of patients with idiopathic chronic pancreatitis (ICP) that have an autoimmune origin is unknown. Three forms of ICP have been described: pseudotumoral, duct-destructive, and usual chronic pancreatitis. The aim of this study was to identify autoimmune stigmata in the 3 forms. Methods: All patients who underwent exploration for ICP were included. The following data were recorded: examination by an internal medicine specialist, autoantibodies and immunoglobulin screening, and pancreatic duct imaging. Results: Sixty patients were included (pseudotumoral, n = 11; duct-destructive, n = 27; usual, n = 22). There were no significant differences among the 3 types with regard to sex ratio, age, frequency of acute pancreatitis, or obstructive jaundice. Pancreatic calcifications were seen only in the usual form (81%; P = .0001). Autoimmune disease was present in 10 patients: ulcerative colitis in 5 patients, primary sclerosing cholangitis in 2 patients, and Sjögren's syndrome, Hashimoto's thyroiditis, and Graves' disease in 1 patient each. Autoimmune diseases were not more frequent in patients with pseudotumoral (36%) or duct-destructive (19%) forms than in those with the usual form (5%, P = .06). Immunoglobulin G4 levels were increased in 2 of 6 in the pseudotumoral, 1 of 9 in the duct-destructive, and 0 of 12 patients in the usual group. Combining clinical and biochemical autoimmune parameters, 24 patients (40%) had at least 1 autoimmune marker or disease. Conclusions: Clinical or biochemical autoimmune stigmata are present in 40% of patients with ICP. Autoimmune mechanisms may be frequent in idiopathic pancreatitis.