Two Cases of Autoimmune Pancreatitis with Coexisting Features of Tumor-Forming Pancreatitis.

Case 1: A 61-year-old male was hospitalized for evaluation of jaundice. The antinuclear antibody ANA titer was 160, and rheumatoid factor RF was positive. Contrast abdominal CT showed di#use enlargement of the pancreas and a mass in the pancreatic head. ERCP revealed localized narrowing in the main pancreatic duct in the pancreatic body. The patient was diagnosed as having autoimmune pancreatitis AIP. Treatment with predonisolone PSL improved the pancreatic enlargement and reduced the size of the mass in the pancreatic head. Case 2: A 74-year-old male was hospitalized with suspected cancer of the pancreatic head. Serum IgG was 2,212 mgdl, IgG4 was 915 mgdl, and the anti-DNA antibody titer was 4. Abdominal US and abdominal contrast CT showed di#use enlargement of the pancreas and a mass in the pancreatic head. As the jaundice decreased with endoscopic naso-biliary drainage, the pancreatic enlarge- ment improved, and the mass in the pancreatic head decreased in size. Based on the clinical course, the patient was diagnosed with AIP. Both of these patients appear to have had AIP with coexisting features of tumor-forming pancreatitis TFP. Thus, AIP should be considered as an etiology of nonalcoholic TFP. One of the two patients initially diagnosed based on the 2002 diagnostic criteria for AIP had a confirmatory diagnosis based on the 2006 revised clinical diagnostic criteria for AIP. Patients should be re-evaluated based on the later criteria.