Supplementary Material for: A Giant Urachal Accessory Spleen: Case Report

Accessory spleen (AS) refers to single or multiple splenic tissues which appear outside the relative normal spleen position results from embryonic dysplasia similar in structure and function to the spleen. AS is frequently observed in the splenic hilus and or adjacent to the tail of pancreas, and only a few cases occurred in the pelvic cavity. We present an extremely rare AS case in urachus, which was initially considered as an urachal neoplasm revealed on CT images with big mass. However, the postoperative pathology confirmed it was an AS that had not been reported at urachal before. Urachal AS can be misdiagnosed as a tumor, so it is vital to make an accurate imaging preoperative diagnosis to avoid unnecessary biopsy and surgery.