Subclinical axillary lymphadenopathy due to COVID-19 vaccine seen on mammograms

10th December 2021

Subclinical axillary lymphadenopathy seen on mammography suggests scans are done before or several weeks after COVID-19 vaccination

The presence of subclinical axillary lymphadenopathy (sLAD) on mammography was significantly more likely among women who had received a COVID-19 vaccination, indicating that they should either delay screening or schedule visits before vaccination. This was the finding of a retrospective study by a team from the Baylor University Medical Center, Dallas, USA.

The term lymphadenopathy refers to lymph nodes that are abnormal in size and axillary lymphadenopathy, describes changes in the size and consistency of lymph nodes in the armpit. There are several potential causes of unilateral axillary lymphadenopathy including breast cancer and which therefore warrants further diagnostic investigations if these changes are observed during screening. Although the presence of sLAD has been observed in women who have received a COVID-19 vaccination, what remains uncertain, is the proportion of vaccinated women that will develop these lesions after either the Pfizer or Moderna vaccines.

Based on case reports of sLAD in vaccinated women, for the present study, the authors investigated the prevalence of the condition in all women who had attended a breast screening programme since December 2020 until April 2021. Data from medical records included the woman’s vaccination status, the vaccine received and the presence or absence of sLAD on mammography. The researchers cross-referenced prior imaging for all women to ensure that there was no baseline evidence of an axillary lymphadenopathy and excluded women who had presented for diagnostic mammography for a palpable axillary lump or pain and those with a history of breast cancer.

Findings

In total, 1027 women with a mean age range of 56.4 to 63.7 years were included in the analysis. There were 158 who received the Moderna vaccine, 144 (Pfizer) and 725 who had not been vaccinated. From these 1027 women, 43 (4.2%) had an sLAD; 3.3% of those who had been vaccinated compared to 0.9% who were unvaccinated and this difference was statistically significant (p < 0.01).

When comparing the two vaccines, the incidence of unilateral axillary lymphadenopathy was higher among those who received the Pfizer vaccination (13.2% vs 9.5%, Pfizer vs Moderna). Among the 43 women with sLAD and who were recalled after screening, vaccine induced sLAD was more likely to have resolved when re-scanned an average of 46.5 days since their COVID-19 vaccination.

The authors concluded that women who have received a COVID-19 vaccination within 8 weeks of their screening mammogram, were significantly more likely to present with a subclinical axillary lymphadenopathy and that this could result in unnecessary further diagnostic workload. They suggested that providers should either delay screening mammograms by 8 weeks in patients who have been vaccinated or that screening should be undertaken before vaccination to avoid unnecessary follow-up.

Citation

Raj S et al. COVID-19 vaccine-associated subclinical axillary lymphadenopathy on screening mammogram Acad Radiol 2021