Unilateral axillary lymph node fluorodeoxyglucose uptakes after coronavirus disease ۲۰۱۹ vaccination

Vaccination against coronavirus disease ۲۰۱۹ (COVID-۱۹) started in early December ۲۰۲۰ worldwide, and healthcare workers in Japan were vaccinated in February ۲۰۲۱. We encountered three patients who underwent ۱۸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for cancer screening at our institution, showing FDG uptakes in the axillary lymph nodes, which seemed to be reactive changes. Two of them were males in their ۴۰s and one was a female in her ۵۰s; all of them were healthcare workers. The medical history revealed that they received the Pfizer-BioNTech COVID-۱۹ vaccination twice at their left shoulders before the FDG PET/CT examination. The degree of FDG uptakes were maximum standardized uptake value (SUVmax)=۳.۲–۹.۹, SUVmax=۵.۹–۱۰.۳, and SUVmax=۲.۸–۷.۹, respectively. They were diagnosed with reactive lymph nodes because of vaccination owing to the absence of abnormal FDG PET/CT findings at other sites. As COVID-۱۹ vaccination becomes more widespread in Japan, radiologists should be aware of these findings to avoid misdiagnosis of FDG uptakes in pathological lymph nodes and to prevent unnecessary additional examinations. Recently, similar FDG PET/CT findings have been reported after receiving the COVID-۱۹ vaccination, and we will report it with a literature review.

Keywords:

COVID-۱۹ , Vaccination , PET/CT , Axillary lymph nodes , ۱۸F-FDG uptake