Morphological changes after steroid therapy in autoimmune pancreatitis

Background: Although many patients with autoimmune pancreatitis undergo steroid therapy, detailed evaluation of morphological changes in the pancreas and bile duct following therapy has not been performed in this disease. In this study serological and morphological changes occurring during steroid treatment of autoimmune pancreatitis are comparatively examined. Methods: Ten patients with autoimmune pancreatitis were treated with corticosteroids. Morphological findings were: pancreatic enlargement (n = 9), irregular narrowing of the main pancreatic duct ( n = 10), and biliary stenosis ( n = 9). An initial dose of prednisolone was 40 - 30 mg/day, and this was tapered by 5 mg every 1 - 2 weeks. All patients underwent ultrasound and serological testing 1 - 2 weeks after commencing medication, followed by weekly serological testing and by CT and endoscopic retrograde cholangiopancreatography after 1-2 months. Radiological and serological changes were compared. Results: All 10 patients were responsive to steroid therapy. Pancreatic size normalized within 1 month; however, irregularity of the pancreatic duct remained in 6 patients. Rigidity or lateral deformity of the bile duct remained in 3 patients and biliary stenosis persisted in 5. Four patients in whom elevated serum IgG4 failed to normalize also showed incomplete morphological improvement. Three patients with complete improvement of the pancreatic duct stopped medication, but recurrence of pancreatitis did not occur. Conclusions: Although steroid therapy was morphologically and serologically effective in patients with autoimmune pancreatitis, cholangiopancreatographic abnormalities remained in many patients. Morphological improvement on cholangiopancreatography and normalization of serum IgG4 after steroid therapy appeared to be good indicators for discontinuing medication in patients with autoimmune pancreatitis.