Heterotopic accessory spleen with squamous epithelial cyst in pancreas mimicking other pancreatic tumor: a case report

A 49-year-old female undergoing a periodic health examination at other hospital revealed a mass in the tail of pancreas. The patient denied any personal history of surgery except subtotal hysterectomy because of multiple myomas in uterus 7 years ago, family history of abdominal cancer and trauma. Physical examination and laboratory finding (including tumor marker) were unremarkable. Chest X-ray result was normal. Contrast enhanced ultrasound (CEUS) examination showed a well-defined hypoechoic pancreatic mass which was suggestive of solid pseudopapillary tumor. Contrast enhanced computed tomography (CE-CT) of the abdomen revealed a mass of hypodensity suggestive of intraductal papillary mucinous neoplasm. Because of the risk of bleeding and exclusion of surgical contraindications, patient underwent laparoscopic surgery. Intraoperatively, a solid mass was identified in the tail of pancreas, the intraoperative frozen pathological examination suggested a heterotopic accessary spleen (HAS) with squamous epithelial cyst. Partial pancreatectomy was performed. The uniqueness of this case is that the spleen can be ectopic to the pancreas, what is even more unexpected is that the HAS undergone cystic change. When encountering a pancreatic mass, we need to think about the possibility of HAS. In conclusion, it is important to diagnose HAS with squamous cyst in the pancreatic tail presenting as other pancreatic masses.