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

## TL;DR

A rare case of a large accessory spleen in the right retroperitoneum was mistaken for sarcoma and required surgical removal for diagnosis.

## Contribution

This paper presents a rare clinical case of a right-sided retroperitoneal accessory spleen mimicking sarcoma.

## Key findings

- Right-sided retroperitoneal accessory spleens are extremely rare.
- Preoperative diagnosis of accessory spleen is uncommon, often requiring surgical confirmation.
- Laparotomy resection was used to manage the large mass in this case.

## Abstract

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.