Interesting ImagesPotential Pitfall of Fluciclovine PET/CT in Castrate-Resistant Prostate Cancer With Adrenal MetastasisQi, Jin MD; Nguyen, Nghi C. MD, PhD Author Information From the Department of Radiology, University of Texas, Southwestern Medical Center, Dallas, TX. Received for publication March 10, 2022; revision accepted June 30, 2022. Conflicts of interest and sources of funding: none declared. Correspondence to: Nghi C. Nguyen, MD, PhD, Department of Radiology, University of Texas Southwestern, 5323 Harry Hines Blvd, Dallas, TX 75390. E-mail: [email protected]. Clinical Nuclear Medicine: December 2022 - Volume 47 - Issue 12 - p 1061-1062 doi: 10.1097/RLU.0000000000004373 Buy Metrics Abstract An 83-year-old man with castrate-resistant prostate cancer underwent an 18F-fluciclovine PET/CT scan, which was negative for local disease recurrence or locoregional lymphadenopathy, but there were multiple fluciclovine-avid bone metastases. In addition, mildly avid bilateral adrenal nodules were thought to be benign. However, on follow-up PET/CT 10 months later, while on additional therapy with enzalutamide, the bilateral nodules became mass lesions with interval decreased fluciclovine avidity. Adrenal metastases were suspected given their rapid growth, with subsequent CT-guided biopsy revealing metastatic prostate cancer without tumor necrosis. This false-negative case highlights the diagnostic challenge of fluciclovine PET in characterizing adrenal lesions. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.