Challenging diagnostic of an accessory spleen mimicking a retroperitoneal tumor: A case report and review of the literature

Background: The accessory spleen is a congenital defect with an additional splenic tissue to the native spleen due to an incomplete fusion of splenic masses during the embryologic period. The preoperative diagnosis is usually mistaken for a retroperitoneal neoplasm. The aim of the present manuscript is to highlight the diagnostic difficulties of a retroperitoneal spleen. Case presentation: A 41-year-old woman was admitted to the surgical department for an abdominal mass discovered by auto palpation associated with a left lower quadrant pain. The computed tomographic scan showed a heterogeneous and partially necrotic retroperitoneal mass located along the left primitive iliac vessels . Arterial supply to the mass arose from the aorta and the left iliac vessel. The spleen was normal. MRI examination showed a left retroperitoneal heterogeneous and necrotic mass, surrounding the iliac vessels extended from the aortic to the left iliac bifurcation, hyper vascularized at the arterial time with a peripheral capsule intensely enhanced, and there were two other lateroaortic vascularized masses. The patient underwent laparotomy resection of the retroperitoneal mass. The examination of the specimen concluded to an accessory spleen. The postoperative course was uneventful. Conclusion: An accessory spleen on the retroperitoneal position is extremely uncommon. Preoperative diagnosis is still challenging. The main misdiagnosis is neoplastic disease.