As mass COVID-19 vaccination is underway, radiologists are encountering transient FDG uptake in normal or enlarged axillary, supraclavicular, and cervical lymph nodes after ipsilateral deltoid vaccination. This phenomenon may confound interpretation in oncology patients undergoing FDG PET/CT. In this article, we present our institutional approach for management of COVID-19 vaccine-related lymphadenopathy on FDG PET/CT based on our early experience. We suggest performing PET/CT at least two weeks after vaccination in patients with a cancer for which interpretation is anticipated to be potentially impacted by the vaccination, though optimally 4-6 weeks after vaccination given increased immunogenicity of mRNA vaccines and potentially longer time for resolution than lymphadenopathy after other vaccines. PET/CT should not be delayed when clinically indicated to be performed sooner. Details regarding vaccination should be collected at the time of PET/CT to facilitate interpretation. Follow-up recommendations for post-vaccination lymphadenopathy are provided, considering the lymph node's morphology and likely clinical relevance. Consideration should also be given to administering the vaccine in the arm contralateral to a unilateral cancer to avoid potentially confounding FDG uptake on the side of cancer. Our preliminary experience and suggested institutional experience should guide radiologists in the management of oncology patients undergoing PET/CT after COVID-19 vaccination.

RadioGraphics continues to publish radiologic-pathologic case material selected from the American Institute for Radiologic Pathology (AIRP) “best case” presentations. The AIRP conducts a 4-week Radiologic Pathology Correlation Course, which is offered five times per year. On the penultimate day of the course, the best case presentation is held at the American Film Institute Silver Theater and Cultural Center in Silver Spring, Md. The AIRP faculty identifies the best cases, from each organ system, brought by the resident attendees. One or more of the best cases from each of the five courses are then solicited for publication in RadioGraphics. These cases emphasize the importance of radiologic-pathologic correlation in the imaging evaluation and diagnosis of diseases encountered at the institute and its predecessor, the Armed Forces Institute of Pathology (AFIP).