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

Abstract

ObjectivesReactive 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 18 F-fluorodeoxyglucose positron emission tomographycomputed tomography ( 18 F-FDG PET-CT), and its relationship with gender, age and vaccine type. MethodsA retrospective study was performed. Two-hundred and four eligible patients had 18 F-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. ResultsThirty-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. ConclusionsPhysicians' awareness of COVID-19 vaccine-related reactive ALN on 18 F-FDG PET-CT is important to avoid inappropriate upstaging of cancers.

COVID-19 vaccination, implications for PET/CT image interpretation and future perspectives

“…The percentage of positivity was higher after the second dose with regard to both deltoid muscle and lymph-nodal uptake. The incidence of hypermetabolic lymph nodes appeared to be higher in the first few weeks after the injection and seems to decrease over time [ 2 , 5 , 6 , 10 , 13 – 15 ], although they may be visible even after 10 weeks [ 3 , 6 ]. Vaccine-related axillar uptake following the third vaccination usually persists just for few days (up to 5 days), rarely interfering with images’ interpretation [ 17 ].…”

“…Positive lymph nodes were observed less frequently in elderly (≥ 64 years) patients (22 versus 37%, respectively). El-Sayed et al [6] evaluated the incidence and the temporal extent of vaccination-related hypermetabolic lymph nodes with two different vaccine types (Pfizer-BioNTech or Vaxzevria). They found "hot" ipsilateral lymph nodes in 36% of cases up to 10-week post-vaccination, although intensity and frequency of vaccination-related hypermetabolic lymph nodes decreased over time.…”

Misdiagnosis of Reactive Lymphadenopathy Remotely After COVID-19 Vaccination: A Case Report and Literature Review

“…In CDC reports, lymphadenopathy occurred within 2 to 4 days after vaccination with Moderna and lasted for 1 to 2 days (11), and the duration in radiologic observational reports was longer (between 4 days and 10 weeks) (12)(13)(14)(15)(16)(17)(18). However, most of these cases were retrospective studies in the patients who recently received the COVID-19 vaccine and underwent positron emission tomography (PET).…”

Discrimination between Benign and Malignant Post-SARS-CoV-2 Vaccination Lymphadenopathy is Feasible

“…Although ALP/ALN is not rare, it is a frequent complication of all approved SARS-CoV-2 vaccines. In a retrospective study of 204 patients undergoing 18 F-fluorodeoxyglucose (FDG)-PET CT between January and March 2021, 36% of patients had ALP/ALN [ 4 ].…”