[A Case of Retroperitoneal Leiomyosarcoma with Inferior Vena Cava Invasion Undergoing Resection and Reconstruction of the Inferior Vena Cava and Left Renal Vein].

Retroperitoneal leiomyosarcoma is a rare disease, and the prognosis is relatively poor. Here, we report a case in which radical resection of retroperitoneal leiomyosarcoma was possible with combined resection and reconstruction of the inferior vena cava and left renal vein. An 81-year-old patient was referred to our hospital for treatment of a retroperitoneal tumor. After detailed examination, a 5 cm-sized hypervascular solid tumor with invasion from the inferior vena cava(IVC)to the left renal vein(LRV)and tumor thrombus was found. The resection was performed, in which the IVC and LRV were resected together, and IVC was anastomosed end-to-end, and LRV stump and IVC were anastomosed end-to-side. The pathological diagnosis was leiomyosarcoma, and the patient has been undergoing follow-up observation for 1.5 years, with no recurrence. Retroperitoneal leiomyosarcoma is a rare disease, and the only treatment is complete resection of the tumor, including IVC. Even if complete resection is performed, the prognosis is poor, however, there have been a small number of reported cases of long-term survival after complete resection, so aggressive treatment is recommended.