Long-term outcome of autoimmune pancreatitis after oral prednisolone therapy

Objective We investigated the long-term outcome of autoimmune pancreatitis (AIP) including morphological changes in the pancreas, pancreatic duct, biliary tract, pancreatic function, and changes in the clinical manifestations after oral prednisolone (PSL) therapy. Patients and Methods We prospectively followed 12 patients for a period of over 12 months ( median follow-up period: 41 months; range: from 13 to 133 months). All twelve patients were treated with PSL. The morphological findings consisted of pancreatic enlargement (n=12), an irregularly narrowed main pancreatic duct ( n=12), and bile duct stricture ( n=10), and salivary gland swelling was observed in six patients. The initial dose of PSL was 30-40 mg/day, and it was subsequently tapered. Results All 12 patients responded to PSL therapy. The enlargement of the pancreas and the irregularly narrowed main pancreatic duct improved to almost normal. Pancreatic atrophy developed in four of them ( 4/12, 33%), but no pancreatic calcification was observed in any of the patients. The bile duct stricture improved to various degrees in all 10 patients, but it persisted in the lower part of the bile duct in four of them ( 4/10, 40%). The salivary gland swelling also improved after PSL therapy. There was no recurrence of enlargement of the pancreas or irregularly narrowed main pancreatic duct after PSL therapy, but the bile duct stricture recurred in one case, and in three cases there was a relapse of salivary gland swelling that required a temporary increase in PSL dose during tapering. No deterioration of pancreatic exocrine function was detected in any of the patients. A malignant tumor was diagnosed in two patients during PSL therapy: early gastric cancer in one and rectal cancer in the other. All patients are alive. Conclusions AIP treated with PSL has a favorable long-term outcome based on the morphological findings and assessments of pancreatic function. However, since two of the twelve patients developed a malignancy during PSL therapy, strict follow up should be part of the management of AIP.