Primary cardiac rhabdomyosarcoma (primary rhabdomyosarcoma of heart) is the most common cardiac malignant tumor except for angiosarcoma that arises from myocardial tissue. Cardiac rhabdomyosarcoma is considered to be a developmental abnormality, which may be differentiated from primitive mesenchymal cells and is mostly congenital. From a pathological point of view, rhabdomyosarcoma is a common and highly malignant mesenchymal tumor that often occurs in the limbs and is mostly located in the muscle or its vicinity. It is nodular or lobed, and the cross-section is fish-like, grayish white or grayish red. Hemorrhage and necrosis are often seen. Under the microscope, the tumor is mainly composed of striated muscle cells at various stages of differentiation.