Cardiac angiosarcomas are extremely rare in childhood, they are rapidly progressive tumours that often present themselves as diagnostic dilemmas, resulting in delayed diagnosis. Also, extracardiac manifestations, including abdominal pain, are extremely rare in patients with intracardiac tumors. We herein present the case of a 15-year-old girl who presented with abdominal pain. Echocardiography and thoracic computed tomography showed right atrial mass. The patient underwent surgery, chemotherapy, and radiotherapy. Eight months after treatment, abdominal recurrence was detected. The abdominal mass was resected, and radiotherapy and new chemotherapy protocol were given. The present case illustrates a rare case of primary cardiac angiosarcoma posing a diagnostic dilemma in an adolescent girl.