Rare presentation of a right retroperitoneal accessory spleen: A case report.

An accessory spleen is a congenital malformation, which is defined as ectopic splenic parenchyma. Here, an extremely rare case of a right retroperitoneal accessory spleen, mimicking a retroperitoneal neoplasm, is reported. A 40-year-old woman was referred following the incidental detection of a retroperitoneal neoplasm. Computed tomography and magnetic resonance imaging scans confirmed the presence of a retroperitoneal neoplasm at the hepatorenal recess. Retroperitoneoscopic excision was conducted, with excellent results. Pathological examination of the resected specimen revealed splenic tissue. In conjunction with a review of the literature and a discussion of the salient radiological features, the present case highlights the requirement for accurate preoperative diagnosis of an accessory spleen in the right retroperitoneal space, in order to avoid unnecessary surgical intervention.