Swollen lymph glands after vaccine can cause mammogram worries

Coordinate scheduling to help alleviate unnecessary concerns

Swollen lymph nodes, a minor side effect of the COVID-19 vaccine, have shown up as abnormal-looking results on some women’s regular screening mammograms in the past few months.  

But new vaccine scheduling guidelines can help women avoid the results — and unnecessary worry and testing — says Summer Chaudhry, MD, medical director of the Breast Healthcare Center at Missouri Baptist Medical Center.

Lymph nodes are part of the immune system. Although they’re found throughout the body, they cluster in the neck, axilla (armpit), abdomen and groin. Their function is to clear lymphatic fluid from the body, which increases during infection or inflammation. Swollen lymph nodes are a sign the body is fighting off the infection.

Swollen lymph nodes are a known and temporary side effect after receiving a vaccine and are a sign the immune system is responding to the vaccine.

But lymph nodes also can enlarge when a cancer spreads, or metastasizes, through the body beyond where it originated.

Unfortunately, mammograms can’t tell the difference. So, when swollen lymph nodes show up on a woman’s screening mammogram, it calls for further testing.

“Patients with more advanced breast cancer often have enlarged lymph nodes in the axilla,” says Dr. Chaudhry. “When we see enlarged or prominent lymph nodes on the screening mammogram within the axilla, the patient is called back for additional evaluation, which can include ultrasound of the breast and axilla.”

Breast radiologists occasionally see patients with swollen lymph nodes after other vaccines, such as the yearly flu vaccine or the human papilloma virus (HPV) vaccine. But in the past several months, with mass vaccinations going on across the world, they’ve seen more cases of swollen nodes after the Moderna and Pfizer COVID-19 vaccines, says Dr. Chaudhry.

The result has been more follow-up testing — and more worry — for some women.

Dr. Chaudhry recommends that women consider the Society of Breast Imaging’s guidelines:  If possible, have your screening mammogram prior to getting the first dose of the COVID-19 vaccine or 4-6 weeks following the second dose. “This will usually allow enough time for the swollen lymph nodes to normalize and prevent an unnecessary evaluation,” she says.

Dr. Chaudhry offers two further reminders.

First, patients with a specific breast complaint such as a palpable lump, unexplained nipple discharge or nipple retraction shouldn’t delay their mammogram. They should see their doctor immediately for further evaluation as necessary.  

Second, she says, patients should remember that being called back after their screening mammography does not mean they have cancer. It simply means that a more detailed evaluation is needed.

“Although being called back can cause anxiety, it allows for more thorough evaluation and we can often diagnose smaller and early-stage cancers,” she says. “If patients have enlarged lymph nodes on screening mammography, even several months after the vaccine, surgery or other systemic illnesses, serial ultrasound evaluation allows us to monitor the lymph nodes more frequently and ascertain that the enlargement is due to infection/inflammation and not malignancy.”

While most women would rather avoid vaccine side effects as well as the experience of being called back after a mammogram, says Dr. Chaudhry, any inconvenience and annoyance is far outweighed by one benefit — a healthier future. 

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