Lymphoepithelial cyst of the pancreas that was difficult to distinguish from branch duct-type intraductal papillary mucinous neoplasm: Report of a case

A 58-year-old woman was admitted to our hospital to optimize the management of her diabetes mellitus. A computed tomography (CT) scan showed a 30-mmdiameter, multilocular cyst in the head of the pancreas. The tumor markers, including DUPAN 2, SPAN-1, and carbohydrate antigen 19-9, were within the normal ranges. A contrast-enhanced CT scan showed a nonenhanced, multilocular cyst. Abdominal magnetic resonance imaging showed a multilocular cyst. Endoscopic retrograde cholangiopancreatography showed that the main pancreatic duct was normal. Based on these findings, we suspected a branch duct type intraductal papillary mucinous neoplasm. A distal pancreatectomy with a splenectomy was performed, since more of the mass was located on the dorsolateral side, inconsistent with the preoperative imaging results. On the resected specimen, a 4-cm-diameter, multilocular cyst containing serous fluid was found. Pathologically, the cyst wall was lined with squamous epithelium surrounded by abundant lymphoid tissue with follicles, consistent with a lymphoepithelial cyst of the pancreas, which is an unusual benign cyst.