Epidermoid cyst in an intrapancreatic accessory spleen is a rare benign lesion that is difficult to diagnose preoperatively. Cyst fluid analysis for biochemistry markers has been widely used to aid the diagnosis of pancreatic cysts. A high cyst fluid carcinoembryonic antigen (CEA) level (>800 ng/mL) is said to be useful in distinguishing intraductal papillary mucinous neoplasm (IPMN) and mucinous cystic neoplasm (MCN) from other non-mucinous cysts. We herein report a case of epidermoid cyst in an intrapancreatic accessory spleen with abnormally high CEA level (3582 ng/mL) in the cyst fluid, suggesting a potential pitfall in using cyst fluid CEA level as an indicator of mucinous neoplasms.