[Leiomyosarcoma Originating from the Renal Vein-A Case Report].

An 83-year-old female was referred to our hospital because of bilateral lower extremity edema. Contrast-enhanced computed tomography(CT)showed an irregular mass, 7 cm in diameter, with central necrosis at the left renal hilum, infiltrating the left renal pelvis and ureteral junction with hydronephrosis. Magnetic resonance imaging(MRI)showed restricted diffusion at the tumor margin. Retroperitoneal tumor resection and left renal resection were performed. Although the tumor was close to the jejunum and the pancreas body and tail and spleen it could be separated from the tumor. The histopathological diagnosis was a solid tumor of spindle and polyrhomboidal cells with necrosis extending from the renal vein wall to the vascular lumen and adventitia. Immunohistochemical staining was positive for α-SMA and weakly positive for desmin. The diagnosis of leiomyosarcoma originating from the renal vein was made because of its continuity with the renal vein. Leiomyosarcoma accounts for 5-7% of soft tissue sarcomas and is the second most common retroperitoneal sarcoma liposarcoma. Sixty percent of vascular leiomyosarcomas originate from the inferior vena cava, while originating from the renal vein are rare. The patient has been free from recurrence and metastasis 1 year after surgery.