After more than a year of anxious waiting, women newly vaccinated against COVID-19 are flocking back to mammography clinics to catch up on routine tests that were delayed by the pandemic. In some cases, they're met with one more pandemic surprise: a false red flag for breast cancer.
Like a sore arm or slight fever, lymph nodes enlarged by the immune system's response to a COVID-19 vaccine are virtually always a sign that the shot vaccine is doing its job. But to the medical specialists who scour mammograms for signs of malignancy, the unexplained appearance of swollen lymph nodes has typically sparked concern and a recommendation that the patient be called back for further testing.
The result has been new uncertainties for women and the doctors who care for them.
If it's a false alarm, women certainly don't need the worry-inducing call reporting an "abnormal reading" on their mammogram. And few welcome the additional tests that tend to follow.
But as much as doctors wish to spare their patients unnecessary angst, they also want to avoid missing a signal that could be important.
"It's a bit of a balancing act," said Dr. Lisa Mullen, a breast imaging specialist at Johns Hopkins University School of Medicine in Baltimore. With many basic questions about the rash of enlarged lymph nodes still unanswered, the world of breast cancer screening has been forced to call some audibles.
The radiologists who scour mammograms for signs of cancer are not easily rattled. They examine thousands of breast images each week and make lots of judgment calls.
It's not very often they are downright flummoxed.
On a typical pre-pandemic day, Dr. Hannah Milch at UCLA Medical Center might have seen one screening mammogram ambiguous enough to recommend further testing. And those cases rarely involved swollen lymph nodes in a woman without a notable risk for breast cancer.
In fact, radiologists say those "axillary" lymph nodes are usually elusive. Studies have shown that no more than .04% of mammograms reveal enlarged lymph nodes in women with no other sign of illness or malignancy. Tucked into the armpit, they are more likely to recede from a mammogram image than to photobomb it.