An extremely rare case of an oversized accessory spleen: case report and review of the literature.

Background: The accessory spleen is a congenital defect characterized by a separated ectopic splenic parenchyma. The size is rarely more than 4 cm. The preoperative diagnosis is prohibitive preoperatively. The aims of the present manuscript were to present the case of a patient with a rare oversize accessory spleen and a review of the literature.

Case Presentation: A 15-year-old boy was admitted to the emergency department following blunt abdominal trauma. The computed tomographic scan showed a traumatic rupture of the spleen and a 7-cm mass at the left side of the retroperitoneal space. Conservative treatment started and aborted after 4 h due to the onset of haemodynamic instability. Splenectomy was performed. An accessory spleen was discovered. A second large mass in the retroperitoneum was diagnosed as a second large accessory spleen that was also left in place. The postoperative course was uneventful, and the patient was discharged on the 7th postoperative day. Seven months later, the CT scan showed viability of both accessory spleens.

Conclusion: An accessory spleen can be variously located and the retroperitoneal position is extremely uncommon. Preoperative diagnosis is still difficult, especially in emergency and as in our case, the literature shows the difficulty of reaching a diagnosis before surgery. The main misdiagnosis is neoplastic disease and for this reason accessory spleen can be wrongly removed. An undiagnosed pre or intra operative retroperitoneal mass, closely to the spleen, have to be managed carefully. The diagnosis of accessory spleen needs to be ever considered as if found, represents a great possibility to conduct a normal life after splenectomy (of main spleen) for trauma.