Incidence of Axillary Adenopathy in Screening or Diagnostic Mammography After COVID-19 Vaccination

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In a single-center retrospective study reported in a research letter in JAMA Oncology, Robinson et al found a vaccine-related axillary adenopathy incidence rate of 3% among women undergoing screening or diagnostic mammography within 90 days of receipt of at least one dose of a COVID-19 vaccine.  

The study included data from 750 women who had received at least one vaccine dose within 90 days before undergoing mammography at the Jacoby Center for Breast Health, Mayo Clinic, Florida, between January 15 and March 22, 2021.

Key Findings

Overall, 223 women underwent mammography after a first dose of vaccine and 525 after a second dose (unknown status for 2). Of the 750 women, 23 (3%) had had axillary adenopathy on mammography.

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Presence of adenopathy symptoms (2 of 23 with vs 3 of 727 women without adenopathy on mammography) was associated with vaccine-related adenopathy (P = .01). Presence of vaccine- associated adenopathy was not significantly associated with age (median = 64 vs 67 years, P = .29) or type of vaccine (overall P = .70).

Most women with adenopathy had received two vaccine doses (18 vs 4 after 1 dose, and 1 with unknown status), although the difference in risk after the first vs second dose was not statistically significant (P = .34).

The median time after vaccine dose to mammography was 10 days (range = 1–28 days) in women with adenopathy vs 18 days (range = 1–85 days) in those without adenopathy (P < .001). Adenopathy rates decreased as days from vaccination increased: 15 (5.3%) of 283 for 1 to 14 days, 8 (2.9%) of 272 for 15 to 28 days, and 0 (0%) of 195 for longer than 28 days (P = .01). A potential cutoff of 22.5 days for adenopathy vs no adenopathy was associated with a receiver operating characteristic area under the curve value of 0.72 (95% confidence interval = 0.63–0.81).

Mammography findings included a single enlarged lymph node, multiple enlarged nodes, and adenopathy with soft-tissue stranding. Among 17 women undergoing subsequent ultrasonography, findings ranged from mildly prominent nodes with preserved fatty hilum to rounded nodes with apparent loss of fatty hilum.

The investigators stated, “While the incidence of COVID-19 vaccine–induced adenopathy in our study appeared to be low, at 3% compared with 16% of self-reported axillary swelling in previous COVID-19 vaccine trials, this incidence is still higher than axillary adenopathy in otherwise normal mammography, which has been reported as 0.02% to 0.04%. Therefore, routine inquiring about recent history of COVID-19 vaccination is warranted.”

They concluded, “As COVID-19 vaccination is rolling out around the world, this study offers timing considerations and possible findings for breast imaging following vaccination. Further studies are needed to guide future recommendations for following up with patients with adenopathy after vaccination and evaluating findings with other imaging modalities.”

Saranya Chumsri, MD, of the Division of Hematology and Medical Oncology, Mayo Clinic, Jacksonville, is the corresponding author for the JAMA Oncology article.

Disclosure: The study was supported by the Mayo Clinic. For full disclosures of the study authors, visit

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.