Painful Armpit Swelling After COVID Vaccine: Next Steps?

Andrew M. Kaunitz, MD

Andrew M. Kaunitz, MD: Several weeks ago, I saw a new patient, a woman in her early 50s who reported "swelling in my armpit." In the past week, she had noted that tissue in the upper outer quadrant of her left breast and axilla seemed puffy, a bit tender, and more prominent than on her right side. She had no recent fever.

She had no personal or family history of breast cancer. Two previous screening mammograms had been read as normal. She underwent placement of breast implants when she was in her late 20s.

Examination of the patient, both seated and supine, revealed symmetric breasts with implants, no skin changes, and no palpable axillary lymph nodes. The patient pointed to what she considered the area of concern — the somewhat tender and swollen upper outer quadrant of her left breast and the underlying pectoralis major muscle.

Our University of Florida breast imaging center is next door to the ambulatory obstetrics/gynecology suite, so I walked over to talk with my colleague Dr Pamela Hatch, a radiologist with fellowship training in breast imaging. Dr Hatch returned with me, where she spoke with and examined the patient.

Parlyn D. Hatch, MD

Pamela D. Hatch, MD: I examined the patient and agreed that some axillary tail fullness was present, but no distinct masses. The exam also revealed that the patient's discomfort extended into the left axilla.

This brought to mind a discussion I'd had recently with my colleague Dr Haley Letter. Dr Letter had seen online discussions among members of the Society of Breast Imaging (SBI), who were talking about patients presenting with swollen lymph nodes on the side they received the COVID vaccine injection.

Breast imagers have long been aware that vaccinations administered in the deltoid area can result in transient unilateral axillary lymphadenopathy. Both Mehta and colleagues and Edmonds and colleagues have written that the occurrence of axillary lymphadenopathy was particularly frequent after mRNA COVID-19 vaccination.

Upon inquiry, the patient revealed that she had indeed received the first dose of COVID-19 vaccine 12 days earlier, in her left arm. Because her most recent screening mammogram had been done more than 6 months earlier, and the symptoms involved both the axillary tail and the axilla, I recommended that Dr Kaunitz order a diagnostic mammogram and sonogram of the left breast and a left breast sonogram.

Enlarged lymph nodes are often visible on mammography (Figure 1).

Figure 1. Mammogram showing enlarged axillary lymph nodes.

Mammographic images (Figure 2) in our patient did not show enlarged axillary lymph nodes. The patient has a breast implant in place, but no mammographic abnormalities were seen.

Figure 2. Mammographic images of the left breast, with palpable and pain markers indicated.

Ultrasound can often reveal deeper nodes not seen on mammography or felt on exam. As suspected, the left breast/left axillary ultrasound demonstrated lymphadenopathy, confirmed by thickening of the lymph node cortex to greater than 3 mm (Figures 3 and 4).

Figure 3. Ultrasound demonstrating one of the markedly swollen lymph nodes in the left axilla, with a nearby node that still appears normal.

Figure 4a. Lymph node with thickened cortex in the patient's left axilla. 4b. Cortex of a normal lymph node in the pain-free right axilla.

Evaluation and Follow-up

Hatch: Because unilateral lymphadenopathy can be an indication of breast cancer, the SBI has issued guidance to prevent unnecessary evaluation and foster appropriate follow-up of patients who have unilateral lymphadenopathy on routine screening mammograms after COVID vaccination. The guidance includes the following:

Consider obtaining the following information on patient intake forms: COVID-19 vaccination status; timing and side (left vs right arm) of vaccination. To minimize patient anxiety, consider including this introductory statement: Vaccines of all types can result in temporary swelling of the lymph nodes, which may be a sign that the body is making antibodies in response to the vaccine, as intended.
Unilateral axillary adenopathy on screening exams warrants a BI-RADS (Breast Imaging Reporting and Database System) category 0 assessment to allow further evaluation of the ipsilateral breast and documentation of medical history, including COVID-19 vaccination.
After appropriate diagnostic work-up for unilateral axillary adenopathy in women who received a COVID-19 vaccination in the ipsilateral upper extremity within the preceding 4 weeks, consider a short-term follow-up exam in 4-12 weeks (BI-RADS category 3) after the second vaccine dose.
If axillary adenopathy persists after short-term follow up, consider lymph node sampling to exclude breast and nonbreast cancer.

The SBI also recommends that, if possible and when it does not unduly delay care, clinicians consider scheduling screening exams before the first dose of a COVID-19 vaccination or 4-6 weeks after the second dose of a COVID-19 vaccination. The SBI further advises clinicians to remain alert for additional information regarding assessment and follow up of these patients.

This patient's imaging findings have been assessed as BI-RADS category 3, with the recommendation that Dr Kaunitz order follow-up imaging 3 months after the patient's second vaccination dose.

Kaunitz: One of the attributes I appreciate about the setting I practice in is that it facilitates collaboration with colleagues in other specialties. Our use of a common electronic health record makes it easy and quick to contact and hear back from colleagues regarding evaluation and management of patients. I hope all the women's health clinicians reading this have radiology colleagues like Dr Hatch who, through collaboration, can improve the quality of our patients' care.

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