Background <p>Retroperitoneal leiomyosarcoma represents a poor-prognosis malignancy for which current clinical treatment options remain limited. This study may further help bridge the gap in available therapeutic modalities.</p> Case presentation <p>This case report describes a 75-year-old female patient who was admitted to the hospital with right lower abdominal pain and imaging studies suggesting a retroperitoneal mass and consideration of leiomyosarcoma. After the diagnosis was confirmed by imaging analysis combined with puncture biopsy, the patient received chemotherapy with adriamycin (75&#xa0;mg/m²) and dacarbazine (200&#xa0;mg/m²) to shrink the tumor once every 3 weeks for 4 cycles, which resulted in tumor shrinkage, and then underwent resection of the retroperitoneal leiomyosarcoma combined with resection of the inferior vena cava lesions. The retroperitoneal tumor involving the inferior vena cava (IVC) was completely resected without requiring IVC reconstruction during the surgical procedure. Final histopathological analysis confirmed the diagnosis of leiomyosarcoma. The patient demonstrated an uneventful postoperative recovery with no surgical complications, and subsequent follow-up evaluations revealed no evidence of disease recurrence, resulting in substantial improvement in the patient’s quality of life on the basis of standardized oncology performance metrics.</p> Conclusions <p>This case emphasizes the critical role of imaging in diagnosis and surgical strategies. This study provides new ideas for the complete resection of retroperitoneal leiomyosarcoma. More studies are needed in the future to optimize the treatment strategy for this type of tumor.</p>