medwireNews: An analysis of computed tomography (CT) scans from people with thoracic malignancies shows that approximately one in 11 people develop axillary lymphadenopathy following mRNA-based COVID-19 vaccination.
The study, by Mizuki Nishino and colleagues from the Brigham and Women’s Hospital and Dana-Farber Cancer Institute in Boston, Massachusetts, USA, included 232 individuals who received two doses of mRNA-based COVID-19 vaccines between December 2020 and April 2021.
Nishino and team report that 21 (9.0%) people had new unilateral lymphadenopathy in the axilla and subpectoral areas on postvaccine scans relative to prevaccine images taken up to 6 months before vaccination.
Of these, 14 had advanced-stage thoracic malignancies and seven had early-stage disease. Eleven patients were receiving systemic anticancer therapy, while the remaining 10 were not on treatment.
The median short-axis diameter of the largest node was 7 mm, with a range of 5 to 14 mm. The investigators say that this information “is important to establish imaging criteria for this new phenomenon.”
They add that the nodes were less than 10 mm in the short axis in 90% of cases and would therefore “be considered nonpathologic by RECIST” criteria.
However, the authors stress in the Journal of Thoracic Oncology that because “the differentiation of reactive and metastatic nodes is crucial for patients with cancer, further studies with a larger cohort with longer follow-up are needed to identify robust size criteria for vaccine-related lymphadenopathy.”
Individuals had a median of four nodes with lymphadenopathy. The majority (81%) had two or more nodes, while 28% had at least five nodes affected.
In 10 patients, only axillary lymphadenopathy was detected, whereas both axilla and subpectoral nodes were affected in 11 patients.
Nishino et al found that most (86%) lymphadenopathy cases were detected on scans taken a median of 1.7 weeks after receipt of the second vaccine but three patients showed lymphadenopathy on the scans performed between the first and second doses.
The researchers also note that the phenomenon was significantly more common in women (12.5% of 144) than in men (3.4% of 88) and occurred at a higher rate in patients following the Moderna (mRNA-1273) vaccine (21% of 28) than after the Pfizer-BioNtech (BNT162b2) vaccine (7.4% of 204).
Conversely, age, race, smoking status, tumor characteristics, scan type, and postvaccine scan timing all had no significant impact on the incidence of lymphadenopathy.
Nishino and colleagues conclude that their study “provides the first report on the incidence, predisposing factors, and imaging characteristics of vaccine-related lymphadenopathy on CT using the currently available cohort during the mass vaccinations for COVID-19, which can provide a basis for further studies.”
They add: “Though the timing of lymphadenopathy detection largely depends on the timing of scans, it seems that lymphadenopathy occurs shortly after vaccination, and even with one dose.”
medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group
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