A rare huge retroperitoneal accessory spleen mimicking right-sided sarcoma in a female patient: case report and review

Detecting retroperitoneal accessory spleen (AS) requires a high index of suspicion for proper and timely diagnosis. The AS can be found near the hilum of the spleen or wholly or partially embedded in the pancreatic tail, stomach, bowel, mesentery walls, or even in the pelvis. Left-sided retroperitoneal AS is common compared to the right-sided retroperitoneal location, which is very rare. The diagnosis of AS is not common preoperatively when investigating a mass in the other abdominal regions, and the surgical resection can thoroughly confirm the diagnosis. The management of AS is surgical excision through open, laparoscopic, or robotic-assisted techniques, depending on the patient status, the size and location of the mass, and the available treatment modality in the hospital. Here, we described a rare case presentation of a huge right retroperitoneal mass (AS) that was initially suspected as sarcoma and managed by laparotomy resection.