Interesting ImagesA Rare Presentation of Melanoma as a Retroperitoneal Mass Seen on FDG PETYao, Yutang MM*; Liu, Wusong MM†; Zuo, Zhuo MD‡; Cheng, Zhuzhong MD*Author Information From the *PET/CT Center, Department of Nuclear Medicine †Endoscopy Center ‡Department of Pathology, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, People's Republic of China. Received for publication October 28, 2019; revision accepted November 7, 2019. Conflicts of interest and sources of funding: none declared. Y. Y. and W. L. contributed equally to this work and shared joint first authorship. Author's contributions: Y.Y. contributed to the data collection, PET/CT image interpretation, data analysis, and drafting of the article; Z.C., conception of the work, data interpretation, critical revision of the article, and final approval of the version to be published; W.L., data collection and endoscopy image interpretation; and Z.Z., histopathology image interpretation. Correspondence to: Zhuzhong Cheng, MD, PET/CT Center, Department of Nuclear Medicine, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, No. 55, Section 4, South People's Rd, Chengdu 610041, People's Republic of China. E-mail: firstname.lastname@example.org. Online date: January 30, 2020 Clinical Nuclear Medicine: April 2020 - Volume 45 - Issue 4 - p 324-325 doi: 10.1097/RLU.0000000000002920 Buy Metrics Abstract A 55-year-old woman presented with intermittent fatigue and abdominal pain. Ultrasound and CT scan showed a large heterogeneous mass in the retroperitoneum, suggestive of malignancy. 18F-FDG PET/CT was performed for staging. PET/CT images showed a hypermetabolic retroperitoneal mass. Endoscopy revealed a mass infiltrating the duodenum. Eventually, the mass was pathologically proved to be malignant melanoma. Further extensive clinical, radiological, and endoscopic investigations proved the retroperitoneum to be the primary site. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.