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Pragmatic Approach to Managing and Interpreting Breast Imaging After COVID-19 Vaccination

Key findings

  • The manufacturers of the Moderna and Pfizer/BioNTech COVID-19 vaccines documented axillary adenopathy as a potential adverse event before the vaccines were authorized
  • Since 2013, the American College of Radiology has suggested that unilateral axillary adenopathy in the setting of a known inflammatory cause can be assessed as a benign finding
  • Massachusetts General Hospital bases its management of unilateral axillary adenopathy on clinical presentation and imaging findings, as detailed here

On the online forum of the Society of Breast Imaging, clinics have been reporting an increasing number of cases of incidental axillary adenopathy on the side of COVID-19 vaccination.

The manufacturers of the Moderna and Pfizer/BioNTech COVID-19 vaccines documented axillary adenopathy as a potential adverse event in the paperwork filed with the FDA before the vaccines were authorized. For example, 10% of patients reported palpable adenopathy after the first dose of the Moderna vaccine and 14% after the second dose.

In the American Journal of RoentgenologyConstance D. Lehman, MD, PhD, director of the Division of Breast Imaging at Massachusetts General Hospital, and Mass General radiologists Leslie R. Lamb, MD, MSc, and Helen Anne D'Alessandro, MD, note professional society guidance about adenopathy after COVID-19 vaccination, and they explain their department's own approach in detail that encourages vaccinations and not delaying or rescheduling screening exams.

American College of Radiology

The Breast Imaging Reporting and Data System (BI-RADS) is the standard system of describing breast imaging results. Since 2013, the BI-RADS Atlas, fifth edition, has suggested an assessment of BI-RADS 2 (benign finding) for unilateral axillary adenopathy in the setting of a known inflammatory cause.

Society of Breast Imaging (SBI)

The SBI recently posted online guidance for breast imaging around the time of COVID-19 vaccination. Highlights are:

  • Screening examinations should be scheduled prior to the first dose of a COVID-19 vaccine or four to six weeks after the second dose, but only if these measures do not "unduly delay care"
  • Centers should obtain information on intake forms about the timing and laterality of prior COVID-19 vaccinations
  • Where applicable, patients should be assured in written reports in lay language that enlarged nodes are an expected response to COVID-19 vaccines

Mass General Department of Radiology

Mass General encourages recommended breast imaging regardless of vaccination status and bases its management of axillary adenopathy on clinical presentation and imaging findings:

Asymptomatic and COVID-19 vaccination within the past six weeks: Isolated ipsilateral axillary adenopathy is a benign finding (BI-RADS 2). No further imaging is indicated at the time. If the concern persists longer than six weeks after the final vaccine dose, axillary ultrasound is recommended.

The article includes samples of the standard reports Mass General sends to referring clinicians and patients when axillary adenopathy after COVID-19 vaccination is a benign finding.

Palpable isolated unilateral adenopathy more than six weeks after vaccination is managed with targeted ultrasound (with or without mammography).

Adenopathy on the side of vaccination, identified incidentally during imaging work-up for breast sign/symptom: If there is no suspicious imaging finding in the breast, the recommendations above for asymptomatic adenopathy are followed. Suspicious findings are managed at the discretion of the attending radiologist based on suspicion of the lesion, the appearance of adenopathy and/or pathology results.

Patient with current breast cancer (pre/peri treatment): COVID-19 vaccination is encouraged in the contralateral arm or anterolateral thigh. In patients with unilateral adenopathy on the same side as the breast tumor and the same side as (arm) vaccination, the choice between core needle biopsy, imaging and clinical follow-up is at the discretion of the breast surgeon and/or medical or radiation oncologist in consultation with the radiologist.

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Learn more about the Division of Breast Imaging


Radiologists should emphasize areas of broad consensus about the benefits of screening mammography when speaking with patients, referring providers and administrators.


Manisha Bahl, MD, MPH, and Constance D. Lehman, MD, PhD, of the Department of Radiology, and colleagues found that, among breast cancer survivors, digital breast tomosynthesis was associated with a lower abnormal interpretation rate and higher specificity than conventional mammography.