Case Report: A giant dedifferentiated liposarcoma in the retroperitoneum.

This article presents a 60-year-old woman presented with a one-year history of abdominal distension, which acutely worsened over four days prior to admission. Imaging revealed a large retroperitoneal liposarcoma. Exploratory laparotomy identified a massive tumor (approximately 45×40×13 cm, weighing 8 kg) invading the left kidney, adrenal gland, adnexa, left hemicolon, and mesentery. En bloc resection was performed. Postoperative pathology combined with fluorescence in situ hybridization (FISH) testing demonstrated MDM2/CDK4 amplification, confirming dedifferentiated liposarcoma (DDLPS). The patient recovered well postoperatively and was discharged following adjuvant radiotherapy (IMRT; 50 Gy in 25 fractions), chemotherapy (AD regimen), and immunotherapy (sintilimab).Through this case, we mainly understand the characteristics of the disease onset, special diagnosis, and main treatment methods.