Cardiac mass in children is rare and insidious onset, and primary cardiac mass is less than secondary mass. Among the malignant tumours in children with tumour thrombus in the venous system, about 98% of the cases are nephroblastoma. But it is still rare for the tumour thrombus to reach the level of the atrium or even enter the right ventricle. In this case, the child complained of chest tightness and palpitation and went to the doctor and found Wilms tumour complicated with intracardiac tumour thrombus.
