A 40-year-old woman presented with recurrent chest tightness and shortness of breath for 10 days. The echocardiogram and MRI revealed a mass in the right atrium. FDG PET/CT was performed for further evaluation. The images demonstrated abnormally increased activity in the right atrial mass. The result of pathological examination after the surgical removal of the mass was consistent with angiosarcoma. Despite of receiving aggressive therapy including radiation, the patient had recurrent and metastatic malignancy 8 months later.