Features of Systemic Immune Response From COVID-19 Vaccination on 18F-FDG PET/CT

The rapid rollout of COVID-19 vaccination is accompanied by incidental findings on F-18-FDG PET/CT. Most cases describe reactive axillary lymphadenopathy. A 46-year-old woman with previous history of stage 3A breast cancer underwent follow-up F-18-FDG PET/CT, which demonstrated avid left axillary nodes and intense diffuse splenic uptake and moderate diffuse bone marrow uptake. She had been administered COVID-19 vaccination in the left deltoid 1 week earlier and required hospitalization for 24 hours due to fever. Symptoms settled with supportive treatment. One month after the PET/CT scan, she remained well. Sites of uptake were taken to relate to a systemic immune response.

Automated summary

The rapid rollout of COVID-19 vaccination has led to incidental findings on F-18-FDG PET/CT, with most cases involving reactive axillary lymphadenopathy. This study reports a 46-year-old woman with a history of breast cancer who experienced intense uptake in axillary nodes, as well as diffuse uptake in the spleen and bone marrow, after receiving the COVID-19 vaccine. She developed fever and required hospitalization but recovered with supportive treatment. One month later, she remained in good health. The observed uptake sites are believed to be related to a systemic immune response.