[Leiomyosarcoma of the renal vein: a case report].

A 52-year-old male presented with left intermittent abdominal pain, and was subsequently diagnosed with a tumor in the hilum of the left kidney based on computed tomography (CT) and magnetic resonance imaging (MRI) findings. Under suspicion of left renal cancer, we performed a retroperitoneoscopic left nephrectomy. Histopathological features of the resected specimen were compatible with leiomyosarcoma originating from the left renal vein. Immunohistologically, the tumor cells were spindle-shaped, arranged in bundles, and stained positive for a-smooth muscle actin and desmin. The patient was free from recurrence 2 years after surgery. The prognosis of leiomyosarcoma arising from the renal vein has been considered poor. Herein, we provide details of our case and also review 16 cases of leiomyosarcoma of the renal vein in Japan. We conclude that radical tumor resection is necessary for long-term survial.