COVID-19 Vaccine-Associated Subclinical Axillary Lymphadenopathy on Screening Mammogram

Abstract

Background: Women who received a COVID-19 vaccination may display subclinical unilateral axillary lymphadenopathy on screening mammography, which can appear suspicious for malignancy, leading to additional diagnostic evaluation.

Purpose: To evaluate the prevalence of subclinical unilateral axillary lymphadenopathy (sLAD) on screening mammogram in women who received either the first or second dose of the Pfizer-BioNTech (Pfizer) or Moderna COVID-19 vaccines compared to women who have not.

Materials and methods: In this IRB-approved, HIPAA complaint study from 12/14/2020 to 4/14/2021, 1027 patients presented for screening mammography and met study inclusion criteria. Patients with history of baseline lymphadenopathy or prior cancer diagnosis were excluded.

Results: Of the 1027 women, 43 were recalled for unilateral sLAD. 34 women received a COVID-19 vaccination ipsilateral to the sLAD (Pfizer n=19, 44.2%; Moderna n=15, 34.9%), 9 did not (20.9%). Incidence of unilateral axillary sLAD was significantly higher (p-value<0.01) in those who received a COVID-19 vaccination within approximately 7 weeks preceding screening mammogram. 13.2% of patients who received the Pfizer vaccine and 9.5% of patients who received the Moderna vaccine developed sLAD. Moderna's vaccine elicited a more robust reaction in the elderly (Moderna 63.7 years vs. Pfizer 59.7 years). For both vaccines, sLAD resolved on average 46.5 days after the last COVID-19 vaccine (p=0.44).

Conclusion: Women who have received either mRNA COVID-19 vaccines may benefit from scheduling their screening mammogram before vaccination or consider delaying screening mammography 8 weeks. While Pfizer may have an overall more robust immune response, Moderna may elicit a stronger immune response in elderly women.

Summary: Women who received a COVID-19 vaccination before screening mammography were significantly more likely to present with subclinical axillary lymphadenopathy than women who did not receive the vaccine.

Key results: 13.2% of women who received a Pfizer-BioNTech vaccine exhibited subclinical axillary lymphadenopathy compared to 9.5% of those who received the Moderna vaccine. Only 1.2 % of those who did not receive a vaccine presented with subclinical unilateral axillary lymphadenopathy. The average time of resolution of the lymphadenopathy on diagnostic mammogram was 46.5 days overall, with Pfizer-BioNTech taking 50.7 days and Moderna 41.5 days.

Fig 1

55-year-old clinically asymptomatic woman with COVID-19 vaccine-induced lymphadenopathy. (1a) Screening mammogram mediolateral oblique view from 2020 demonstrating no right axillary lymphadenopathy. (1b) Screening mammogram mediolateral oblique view in 2021 – with patient reporting history of COVID-19 vaccination in the right deltoid 3 weeks before – reveals an enlarged, abnormal axillary lymph node. Otherwise, no suspicious mammographic abnormalities are identified in either breast. (1c) Patient returns for diagnostic ultrasound evaluation 5 days after abnormal screening mammogram. Sonogram shows multiple abnormally enlarged lymph nodes with prominent eccentric cortices. Of note, there is some preservation of the fatty hila. (1d) The patient returns in 5 weeks for short-term diagnostic mammogram follow-up which reveals a return of normal appearing axillary lymph nodes and a recommendation to return to normal screening mammography.

Fig 2

38-year-old clinically asymptomatic woman presents for high-risk breast cancer screening Breast MRI with Contrast. Patient reports history of a COVID-19 vaccine administered 2.5 weeks before MRI. In the right axilla, there are multiple enlarged axillary lymph nodes. No suspicious breast MRI evidence of malignancy is otherwise identified in either breast.