Leiomyosarcoma of the renal vein.

A 43-year-old woman was referred to our clinic for evaluation of a left retroperitoneal mass. She presented to our internal medicine department complaining of back pain. Computed tomography (CT) scan revealed a left retroperitoneal mass 55 mm in size in the hilum of the left kidney. Enhanced CT scan and magnetic resonance imaging (MRI) disclosed a poorly staining mass. Metaiodobenzylguanidine scintigraphy demonstrated no accumulation in the mass; moreover, endocrinologic examination was normal. Laparoscopic resection of the left retroperitoneal tumor was attempted; however, strong adhesion between the tumor and the left renal vein was encountered. Thus, left nephrectomy after open conversion was performed. Histological findings indicated leiomyosarcoma originating from the left renal vein. The postoperative course has been uneventful; neither recurrence nor metastasis is evident 2 years postsurgery.