RT Journal Article SR Electronic T1 The incidence and duration of COVID-19 vaccine-related reactive lymphadenopathy on 18F-FDG PET-CT JF Clinical Medicine JO Clin Med FD Royal College of Physicians SP e633 OP e638 DO 10.7861/clinmed.2021-0420 VO 21 IS 6 A1 Mohamed S El-Sayed A1 Godfrey N Wechie A1 Chen Sheng Low A1 Oludolapo Adesanya A1 Nikhil Rao A1 Vincent J Leung YR 2021 UL http://www.rcpjournals.org/content/21/6/e633.abstract AB Objectives Reactive axillary lymph nodes (ALN) may occur post-COVID-19 vaccination. This may be confused with malignant nodal metastases on oncological imaging. We aimed to determine the reactive ALN incidence and duration on 18F-fluorodeoxyglucose positron emission tomography – computed tomography (18F-FDG PET-CT), and its relationship with gender, age and vaccine type.Methods A retrospective study was performed. Two-hundred and four eligible patients had 18F-FDG PET-CT between 01 January 2021 and 31 March 2021, post-vaccination with Pfizer-BioNTech or Oxford-AstraZeneca vaccine. Image analysis was performed on dedicated workstations. SPSS was used for statistical analysis.Results Thirty-six per cent of patients had reactive ALN until 10 weeks post-vaccination; reducing in frequency and intensity with time. Women were more likely to have reactive ALN compared with men. The frequency and intensity were higher in patients aged <65 years compared with those aged ≥65 years. However, no difference was found between both vaccine types in our study cohort.Conclusions Physicians’ awareness of COVID-19 vaccine-related reactive ALN on 18F-FDG PET-CT is important to avoid inappropriate upstaging of cancers.