Interesting ImagesPrimary Atrial Undifferentiated Sarcoma Found on FDG PET/CT Mimicking Cardiac MyxomaWang, Rang MD; Shen, Guohua MD; Tian, Rong MDAuthor Information From the Department of Nuclear Medicine, West China Hospital, Sichuan University, Sichuan, China. Received for publication May 31, 2020; revision accepted June 26, 2020. Conflicts of interest and sources of funding: This study was supported by the Key Projects of the Ministry of Science and Technology (grant 2017YFC0113304). The authors have no conflicts of interest to declare. R.W. and G.S. contributed equally to this work. Correspondence to: Rong Tian, MD, Department of Nuclear Medicine, West China Hospital, Sichuan University, 37 Guoxue Alley, Chengdu 610041, Sichuan, China. E-mail: email@example.com. Clinical Nuclear Medicine: October 2020 - Volume 45 - Issue 10 - p 833-835 doi: 10.1097/RLU.0000000000003236 Buy Metrics Abstract A 52-year-old man had shortness of breath and chest discomfort for 2 months. Chest CT and MRI showed a mass in the left atrium attached to the mitral annulus without obvious enhancement. Initial diagnosis was suspected of myxoma. Preoperative FDG PET/CT demonstrated the corresponding lesion with abnormal FDG uptake, indicating a malignancy. Finally, histopathologic examination revealed primary undifferentiated sarcoma. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.