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. 2021 Nov;21(6):e633-e638.
doi: 10.7861/clinmed.2021-0420.

The incidence and duration of COVID-19 vaccine-related reactive lymphadenopathy on 18F-FDG PET-CT

Mohamed S El-Sayed  1 , Godfrey N Wechie  1 , Chen Sheng Low  1 , Oludolapo Adesanya  1 , Nikhil Rao  1 , Vincent J Leung  1
Affiliations

The incidence and duration of COVID-19 vaccine-related reactive lymphadenopathy on 18F-FDG PET-CT

Mohamed S El-Sayed et al. Clin Med (Lond). 2021 Nov.

Abstract

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.

Keywords: 18F-FDG PET-CT; COVID-19 vaccine; lymphadenopathy.

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Figures

Fig 1.
Fig 1.
Included and excluded patients.18F-FDG PET-CT = 18F-fluorodeoxyglucose positron emission tomography – computed tomography; ALN = axillary lymph nodes.
Fig 2.
Fig 2.
Typical appearance of reactive axillary lymph nodes post-COVID-19 vaccination in one of the study patients. Straight arrow = injection site inflammation in left deltoid muscle (not necessarily seen in all cases); curved arrow = reactive ipsilateral axillary lymph nodes; CT = computed tomography; PET = positron emission tomography.
Fig 3.
Fig 3.
Relation between axillary lymph nodes dSUV and post-vaccination duration (above the 0.7 line indicates avidity).
See this image and copyright information in PMC

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