Malignant tumors of the inferior vena cava (IVC) are very rare. Leiomyosarcoma accounts for 95% of cases. Cross-sectional imaging including computed tomography and magnetic resonance imaging (MRI) is a cornerstone in the orientation diagnosis and assessment of tumor extension. The confirmation is histological. We present the case of an 8- year-old child referred by pediatric surgery for suspected bladder tumor diagnosed on CT scan.