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COVID vaccine side effect could produce abnormal mammogram results, doctors say

Although alarming at first glance, the pattern is mostly harmless and is actually a common side effect of most vaccines.
A radiologist examines the results of mammograms.

As more people receive COVID-19 vaccines, doctors are noticing an uptick in abnormal breast mammograms in otherwise healthy individuals. Although alarming at first glance, the pattern is mostly harmless and is actually a common side effect of most vaccines.

Still, experts suggest following up on any irregular results several weeks after receiving second doses of a coronavirus vaccine to ensure the inflammation is truly a response to the jab.

“We have been seeing swollen lymph nodes for a couple weeks now,” Dr. Holly Marshall, a breast-imaging radiologist at University Hospitals Cleveland Medical Center, told Fox8. “We also see swollen lymph nodes in patients with breast cancer, so that’s the concern there. So we are asking everybody who is having a mammogram if they had the COVID-19 vaccine, what dose, when and what side.”

But don’t worry. Lymph node inflammation, medically known as axillary adenopathy, detected during routine mammograms after COVID-19 vaccination is a telltale sign the body is building protection against the coronavirus.

That’s because the shot primes the body to produce proteins similar to those the virus uses to latch onto human cells. Once the mission is complete, the immune system recognizes these harmless proteins as foreign and begins its production of coronavirus-fighting antibodies, causing some swelling along the way.

Doctors say they are finding these irritated nodes on the same arm that received the COVID-19 vaccine.

“Sometimes with other vaccines, occasionally we will see swollen lymph nodes, but it was a surprise how many we’ve been seeing” after coronavirus shots, Marshall said.

It’s rare to find swollen lymph nodes during mammograms, with the phenomenon reported in 0.02 to 0.04 percent of screenings, according to the Society of Breast Imaging Patient Care and Delivery Committee. It’s also rare following flu, human papilloma and tuberculosis vaccines, “however, high rates” have been reported after COVID-19 shots.

Swelling and tenderness of lymph nodes in the armpit was reported in nearly 12 percent of patients who received one shot of the Moderna COVID-19 vaccine, compared with 5 percent who received a placebo during clinical trials, a Centers for Disease Control and Prevention report says. After the second dose, those percentages rose to 16 percent and 4.3 percent, respectively.

The Pfizer-BioNTech vaccine also caused some lymph node tenderness, according to the report.

However, these rates were based on physical exams, meaning the actual occurrence of axillary adenopathy during mammograms is likely greater, the Society of Breast Imaging said.

“I think any woman who gets a phone call to come back in as a recall from her screening mammogram, that is an anxiety-producing situation,” Dr. Laura Danile, a diagnostic radiology specialist at Charlotte Radiology in North Carolina, told WBTV. “We hope that this does not delay women from getting a mammogram or the vaccine. Right now we feel that both of those are very useful.”

Dr. Marshall of UH Cleveland Medical Center said patients usually see swollen lymph nodes two to four days after their coronavirus vaccine. Two to four weeks later, inflamed nodes should decrease in size. If not, Marshall said, they need to be evaluated.

The Society of Breast Imaging recommended in its Jan. 22 report a short-term follow-up exam four to 12 weeks after a second COVID-19 vaccine dose if a mammogram showed swollen lymph nodes in the armpit area.

And if the condition persists after the short-term follow-up, “consider lymph node sampling to exclude breast and non-breast malignancy,” the group said. Otherwise, try to schedule the X-rays before a first COVID-19 vaccine dose or four to six weeks after the second one.