Intramuscular coronavirus 2019 (COVID-19) vaccinations could induce ipsilateral axillary lymph node reactivity that may be falsely attributed to malignant abnormality, prompting unwarranted interventions, or it may be falsely attributed to vaccination rather than cancer, potentially delaying cancer care. We aimed to investigate Moderna and Pfizer COVID-19 vaccine-related nodal reactivity on ¹⁸F-flurodeoxyglocose (FDG) positron emission tomographic (PET)/computed tomographic (CT) scans.