Interesting ImagesPrimary Pancreatic Yolk Sac Tumor Presenting as Diffusely Enlarged Pancreas in Initial 18F-FDG PET/CTSui, Huimin MD; Zhu, Zhaohui MD, PhD; Li, Zheng MD; Luo, Yaping MDAuthor Information From the Department of Nuclear Medicine, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and PUMC; and Beijing Key Laboratory of Molecular Targeted Diagnosis and Therapy in Nuclear Medicine, Beijing, People’s Republic of China. Received for publication January 19, 2020; revision accepted February 19, 2020. Conflicts of interest and sources of funding: none declared. Correspondence to: Yaping Luo, MD, Department of Nuclear Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College Hospital, No. 1 Shuaifuyuan, Wangfujing St, Dongcheng District, Beijing 100730, People’s Republic of China. E-mail: firstname.lastname@example.org. Online date: April 23, 2020 Clinical Nuclear Medicine: June 2020 - Volume 45 - Issue 6 - p 483-486 doi: 10.1097/RLU.0000000000003038 Buy Metrics Abstract Yolk sac tumor is a rare and highly malignant germ cell tumor. We report a case of yolk sac tumor primarily in the pancreas in a 32-year-old man. He presented with pancreatitis at presentation with significantly increased serum alpha-fetoprotein (AFP). 18F-FDG PET/CT revealed diffuse enlargement of the pancreas in the neck, body, and tail portion with homogeneously increased FDG uptake, similar to the change of pancreatitis. The lesion progressively developed to a huge pancreatic mass in the follow-up images, and endoscopic ultrasonography-guided aspiration biopsy of the pancreatic mass confirmed the diagnosis of yolk sac tumor. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.