18F-Fluciclovine-Avid Axillary Lymph Nodes After COVID-19 Vaccination on PET/CT for Suspected Recurrence of Prostate Cancer

Abnormally increased F-18-FDG avidity of axillary lymph nodes has become a frequent diagnostic dilemma on PET/CT in the current climate of global vaccinations directed against severe acute respiratory syndrome coronavirus 2. This avidity is due to the inflammatory response evoked by vaccines and the nonspecific nature of F-18-FDG uptake, which is increased in both malignant and inflammatory processes. Similarly, F-18-fluciclovine, an amino acid analog indicated for the assessment of biochemical recurrence of prostate cancer, may also demonstrate nonspecific inflammatory uptake. We report a case of F-18-fluciclovine PET/CT obtained for concern about prostate cancer. In this case, isolated avid lymph nodes were seen in the left axilla. A screening questionnaire revealed that the patient had recently received the second dose of the Pfizer-BioNTech coronavirus disease 2019 vaccine in his left shoulder, and hence, the uptake was determined to be reactive. CASE Subsequent of 5 gical detectable was resulting in significant diagnostic challenges with F-18-FDG