Unusual presentation of right-side accessory spleen mimicking a retroperitoneal tumor

An unusual case of right-side retroperitoneal accessory spleen is presented. A 68-year-old man visited our hospital for the management of incidentally detected retroperitoneal mass. The computed tomography scan of the abdomen revealed the presence of a retroperitoneal tumor (4.0 × 3.8 cm) at the right suprarenal space. Laparoscopic excision was carried out with excellent results. On histological examination, the tumor exhibited a structure typical of splenic tissue. This accessory spleen was unusual in its size and location. Though it existed at the right side, surgeons should be aware of the possible existence of accessory spleens for the differential diagnosis of retroperitoneal tumors.