Swollen lymph nodes after COVID vaccine might show up on mammography — but don’t worry

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Dr. Marie Quinn is the Director of Breast Imaging in the Diagnostic Radiology Department at Roswell Park Comprehensive Cancer Center.
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Women who are looking to schedule their annual mammogram might want to make that appointment before getting their first dose of the COVID-19 vaccine. For some women, routine mammograms are showing swollen lymph nodes in the upper arm and armpit area on the side where they’ve received their vaccine. But that’s not a reason to be alarmed, says Marie Quinn, MD, Director of Breast Imaging in the Diagnostic Radiology Department at Roswell Park Comprehensive Cancer Center.

Swollen lymph nodes are an indication that your body is doing what it’s supposed to, responding to the vaccine and making antibodies, Dr. Quinn says. It also isn’t a response unique to the COVID-19 vaccine, as it has been seen on occasion in people who have received other vaccines, including the annual flu shot and the shingles vaccine. Lymph nodes can remain swollen for up to 12 weeks, but for most women, any swelling would be reduced between four and six weeks after receiving a COVID-19 vaccine, she says. 

“We’re currently recommending that women schedule their mammogram for four to six weeks after their second dose,” Dr. Quinn says. “If you’ve had your first dose of the vaccine and you’re due for a mammogram, schedule it for four weeks after the second dose. But if you’re having a breast-related issue, such as a mass, do not wait to schedule your screening.” 

If swelling is noticed during a mammogram and a woman has had a first or second dose of the COVID-19 vaccine within the past month or so, she will be asked to come in for a breast ultrasound within six to eight weeks to make sure the swelling has reduced.

“Lymph nodes are a normal structure in your body that filter your blood. That’s where your immune cells mature,” Dr. Quinn says. “Anything that’s going on in your body — whether that’s having a vaccine or a rash, or bug bites and sunburn in the summer or dry skin in the winter — it affects your lymph nodes.” 

Lymph nodes usually look like kidney beans, she says, and when they’re swollen, the outer area, called the cortex, looks fatter than normal, causing the nodes to look more rounded, like grapes. When the swelling goes down, the lymph nodes go back to looking like kidney beans, all of which can be observed on mammograms, breast MRIs and ultrasounds. 

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“Feeling swollen lymph nodes after a vaccine is a normal response,” she says. 

But because these lymph nodes closest to the vaccine injection site are also important in terms of breast cancer detection, additional imaging is done to ensure confidence in the mammogram findings.

“If you want to decrease your risk of us seeing swollen lymph nodes, come in before you’ve had the vaccine or four to six weeks after you’ve had the second dose,” Dr. Quinn says. 

The mammography team at Roswell Park has been screening women safely for breast cancer and conducting diagnostic screenings since May 2020, when the pandemic was hitting an early peak, she says. The staff at the clinic have been vaccinated against the virus and continue to practice all recommended safety precautions, including wearing masks and regularly sanitizing the equipment and areas where patients wait for their appointments.