Autoimmune pancreatitis mimicking carcinoma of the head of the pancreas: a case report

INTRODUCTION: We report on a case of autoimmune pancreatitis presenting as pancreatic head cancer, which is extremely rare in Iran. Currently, on the PubMed database, no such cases exist. CASE PRESENTATION: A 70-year-old Iranian man presented with recurrent abdominal pain, jaundice and elevated bilirubin and alkaline phosphatase levels. An abdominal computed tomography scan revealed a heterogeneous presence in the pancreatic head as well as dilated intra- and extrahepatic bile ducts. A common bile duct stent had been inserted. Our patient was subsequently diagnosed with pancreatic head cancer. Due to his continued recurrent abdominal pain, our patient returned to the hospital. His levels of bilirubin, alkaline phosphatase and tumor markers were all normal but his immunoglobulin G4 and antinuclear antibodies were extremely high. A biopsy of the pancreatic head heterogeneity by endoscopic ultrasonography was performed. Pathologic samples showed fibrosis associated with lymphoplasmacytic infiltration and no evidence of malignancy. A diagnosis of autoimmune pancreatitis was confirmed, the bile duct stent removed, and an appropriate treatment plan was undertaken. CONCLUSION: Autoimmune pancreatitis should be considered in suspected cases of pancreatic cancer. In these instances, a biopsy of the pancreas will help to differentiate between the two and prevent complications due to disease progression as well as unnecessary surgery.