Intrapancreatic Accessory Spleen with an Epidermoid Cyst: a Malignant Mimicry

With the liberal use of CT scan for clinical diagnosis, clinicians are faced with an increasing number of pancreatic incidentalomas. Compared with other incidentalomas, pancreatic incidentalomas have higher chances of future malignant transformation. There are many differential diagnoses, and epidermoid cyst in an intrapancreatic accessory spleen (ECIPAS) is extremely rare, with only a handful of reports. Preoperative diagnosis is often complicated, and the final diagnosis is usually only made after surgical resection.We report a 34-year-old man who had an incidentally noted 2.8 cm pancreatic tail cystic lesion on a CT scan done for urinary symptoms. The lesion had a solid nodular component that was worrisome for malignancy, and the patient underwent further evaluation with an MRI scan and endoscopic ultrasound of the pancreas. The differential diagnoses of cystic degeneration of neuroendocrine tumour, branch-duct intraductal papillary mucinous neoplasm with worrisome features or ectopic intrapancreatic spleen were made. A multidisciplinary tumour board recommended surgical resection given risk features of malignancy. The patient subsequently underwent a laparoscopic distal pancreatectomy with splenectomy, and histology confirmed the diagnosis of ECIPAS.Imaging characteristics of ECIPAS are non-specific, and most patients have a diagnosis made only after surgery. Therefore, more evidence is warranted for accurate preoperative imaging diagnosis to avoid unnecessary pancreatic surgery, which is not without its risks.