P2322 - Primary Retroperitoneal Mass Due to a Well-Differentiated Giant Liposarcoma

June Tome, MD, Amrit K. Kamboj, MD, Seth Sweetser, MD
Mayo Clinic, Rochester, MN

Introduction: Primary retroperitoneal masses are frequently malignant and may be due to sarcoma, lymphoma, primary germ cell, and neurogenic tumors. Retroperitoneal fibrosis and other benign etiologies comprise a smaller subset of retroperitoneal lesions.

Case Description/Methods: A 45-year-old previously healthy man presented with a 12-month history of insidious onset and progressive unintentional weight loss of 25 pounds, painless abdominal distention, and early satiety. Physical examination demonstrated significant abdominal distention with firmness in the right mid abdomen and a moderate-sized left indirect inguinal hernia. Computed tomography abdomen showed a 33 x 19 x 40 cm heterogeneous fatty mass arising from the left retroperitoneum near the inferior pole of the left kidney (Figure 1). The mass abutted the inferior pole of the spleen and distal pancreas, displaced the transverse colon superiorly and sigmoid colon anteriorly, and extended inferiorly into the pelvis and left inguinal canal. His abdominal organs were compressed into the right lower quadrant. He underwent surgical resection of the left retroperitoneal mass with sigmoid colostomy and left inguinal hernia repair (Figure 2). Pathology demonstrated atypical lipoblasts with hyperchromatic nuclei consistent with a well-differentiated liposarcoma. He recovered well postoperatively and had no evidence of tumor recurrence or metastasis on magnetic resonance imaging at subsequent 4-month and 8-month follow-up visits.

Discussion: Liposarcoma, one of the most common soft tissue sarcomas, typically occurs in adults 50-70 years of age. While the majority of soft tissue sarcomas are present in the upper or lower extremities, other sites of involvement include the retroperitoneum, mediastinum, and head/neck. Liposarcomas are one of the most common causes of a malignant retroperitoneal mass. In those with a retroperitoneal liposarcoma (RPLS), patients may not present with symptoms until the tumor grows large enough to compress or invade the surrounding structures. Giant RPLS is a particularly rare tumor that may cause complications such as bowel obstruction, hemorrhage, and hydronephrosis. The mainstay of treatment is surgical resection via a multidisciplinary team, with postoperative radiotherapy considered on an individual basis. RPLS generally carries a worse prognosis compared to liposarcomas present at other sites and the recurrence rate depends on the histological subtype.



Disclosures:


June Tome, MD, Amrit K. Kamboj, MD, Seth Sweetser, MD. P2322 - Primary Retroperitoneal Mass Due to a Well-Differentiated Giant Liposarcoma, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.