Interesting ImagesA Case of Primary Sinonasal Yolk Sac TumorWang, Peipei MD; Hou, Guozhu MD; Li, Fang MD; Cheng, Xin MDAuthor Information From the Department of Nuclear Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College; and Beijing Key Laboratory of Molecular Targeted Diagnosis and Therapy in Nuclear Medicine, Beijing, China. Received for publication May 20, 2020; revision accepted July 20, 2020. P.W. and G.H. contributed equally to this work. Conflicts of interest and sources of funding: none declared. This work is supported by Chinese Academy of Medical Sciences Initiative for Innovative Medicine (CAMS-2018-I2M-3-001) and the National Natural Science Foundation of China (no. 81201121). Correspondence to: Xin Cheng, MD, Department of Nuclear Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Shuaifuyuan, Wangfujing, Dongcheng District, Beijing 100730, China. E-mail: email@example.com. Clinical Nuclear Medicine: November 2020 - Volume 45 - Issue 11 - p 908-909 doi: 10.1097/RLU.0000000000003265 Buy Metrics Abstract Yolk sac tumor (YST) is a rare and highly malignant germ cell tumor that is extremely rare in the nasal region. Herein, we present a case of biopsy-proven nasal YST admixed with transitional cell carcinoma in a 58-year-old woman. Complementary 18F-FDG PET/CT revealed the only FDG-avid mass in the right nasal cavity. This case indicates that YST could occur in the nasal region primarily, and 18F-FDG PET/CT is a useful tool to distinguish between primary and metastatic lesions. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.