[Leiomyosarcoma of the kidney with tumor thrombus to the inferior vena cava].

A 76-year-old female presented with edema in the bilateral lower legs and computed tomography (CT) subsequently revealed a tumor under the right side of the kidney that extended to the inferior vena cava. Under suspicion of a right renal sarcoma or malignant teratoma, we performed a right nephrectomy and tumor thrombectomy. Histopathological features of the resected specimen were compatible with a leiomyosarcoma originating from either extrarenal blood vessels or muscle fibers of the renal pelvis. Immunohistological findings showed that the tumor cells were spindle-shaped, arranged in bundles, and stained positive for α-smooth muscle actin and desmin. The patient was free from recurrence 10 months after surgery. The prognosis of patients with a renal leiomyosarcoma with venous thrombus has been considered to be poor. Herein, we provide details of our case and conclude that radical tumor resection is necessary for a long-term cure.