Primary intracardiac yolk sac tumor.

A 2-year-old male child presented with fever, complete heart block, and congestive cardiac failure. Echocardiography showed a dumbbell-shaped mass in the right ventricle and right atrium. He was operated on with a provisional diagnosis of rhabdomyoma. Histopathology and immunohistochemistry of the resected tumor revealed a malignant germ cell tumor with predominant yolk sac differentiation.