Although intra-abdominal accessory spleens are commonly found in 10-30% of the general population, epidermoid cyst within an intrapancreatic accessory spleen (ECIPAS) is an extremely rare entity and is often misdiagnosed preoperatively as a cystic malignancy. We present the case of a 51-year-old man who was referred to our clinic because of an incidentally found pancreatic tail cystic mass. Due to CA 19-9 level over 2000 and high suspicion of malignancy, the patient underwent distal pancreatectomy with splenectomy. Histopathological analysis revealed a squamous epithelial lining with splenic parenchyma within the cyst wall, which was consistent with ECIPAS. The patient was discharged on postoperative day 4 without any complication. As this disease may mimic malignancy with no characteristic features in preoperative imaging, it should be considered in the differential diagnosis of pancreatic cystic lesions.