[A case of eosinophilic pancreatitis].

Eosinophilic pancreatitis is a rare disorder that may only be diagnosed after pancreatic resection under the suspection of a pancreatic tumor. We experienced a 65-year-old female patient whose initial presentation suggested pancreatic cancer. Radiologic evaluation revealed a pancreatic mass-like lesion which was obstructing the main pancreatic duct. Endoscopic retrograde cholangiopancreatography (ERCP) showed double duct strictures involving the distal common bile duct and the main pancreatic duct. Serum IgE level was elevated. Percutaneous core needle biopsy with an 18-gauge needle was performed targeting the pancreatic lesion. The biopsy specimen revealed fibrotic interlobular septum and intralobular fibrosis with prominent eosinophilic infiltration. The patient was treated with oral prednisolone (40 mg/day). A plastic stent was inserted into the narrowed common bile duct. After three months of oral steroid therapy, symptoms and signs improved rapidly and serum IgE level was decreased. Abdominal computed tomography and ERCP revealed remission of pancreatic mass-like lesion.