A case of diabetes mellitus accompanied by tumor-forming pancreatitis that was difficult to distinguish from pancreatic cancer

A 44-year-old-man was diagnosed with diabetes in a medical examination and was admitted to our hospital due to hyperglycemia (FPG 285 mg/dL, HbAlc 10.8 %). He had experienced acute pancreatitis on 3 occasions. The laboratory data on admission revealed that the patient's CEA and DUPAN-2 levels were elevated. Abdominal enhanced CT and MRI demonstrated a tumor of 3 cm in diameter in the pancreatic head. Although pancreatic cancer was strongly suspected, a PET scan was negative. A percutaneous biopsy of the pancreas and a cytological analysis of the pancreatic juice were performed and the pathological diagnosis was tumor-forming pancreatitis. The acute onset of diabetes is considered to be a predictive marker of pancreatic cancer. It is very difficult to differentiate tumor-forming pancreatitis from pancreatic cancer. We should therefore make a comprehensive diagnosis using imaging, an analysis of the tumor marker levels, and a pathological examination.