COVID-19 Vaccine-Linked Adenopathies Could Mimic Breast Malignancies

Patients who receive either the Pzifer-BioNTech or Moderna COVID-19 vaccine can experience swollen lymph nodes that could be mistaken for breast malignancies, new research has found.

In an article featuring four case studies, published this week in Clinical Imaging, investigators from Weill Cornell Medicine outlined the appearance of new unilateral axillary adenopathies seen on ultrasound in patients who recently received the first dose of the vaccine.

Hyperplastic axillary nodes are common after the administration of a vaccine that prompts a strong immune response, including the current COVID-19 vaccines. Consequently, radiologists should keep this side effect in mind when viewing breast images, said the team led by Nishi Mehta, M.D., a Weill Cornell body and breast imaging fellow.

“It is important for radiologists to consider recent COVID-19 vaccination history as a possible differential diagnosis for patients with unilateral axillary adenopathy,” the team said. “As COVID-19 vaccines will soon be available to a larger patient population, radiologists should be familiar with the imaging features of COVID-19 vaccine induced hyperplastic adenopathy and its inclusion in a differential for unilateral axillary adenopathy.”

57-year-old female with unilateral left axillary adenopathy noted 8 days after receiving the first dose of the Pfizer-BioNTech Covid-19 vaccine in her left upper extremity. (a) Gray-scale and (b) color Doppler images of a single enlarged left axillary lymph node diffuse cortical thickening. Unremarkable right axilla was documented (c). Credit: Clinical Imaging

According to the study, the four women included had no history of breast cancer, but they had recently received the first dose of the COVID-19 vaccine in their upper arms. But, they all presented with swollen lymph nodes -- some palpable, some visible only on imaging -- and all were recommended for short-term follow-up targeted ultrasound. In addition, based on these findings Mehta’s team made specific follow-up recommendations.

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Case 1: A 59-year-old woman with no personal history, but a family history of breast cancer, presented with a palpable lump in her left axilla. Sonography revealed both an enlarged left axillary lymph node, as well as uniform cortical thickening. She received the Pfizer-BioNTech vaccine nine days prior and was advised to return for short-term follow-up targeted ultrasound.

Case 2: A 42-year-old woman with no personal or family breast cancer history had multiple enlarged left axillary lymph nodes with uniformly thickened cortices appear on screening mammography. According to medical records, she received the Pfizer-BioNTech vaccine five days prior.

Case 3: A 42-year-old woman with no personal or family breast cancer history had diffuse cortical thickening of the left axillary lymph node appear on follow-up of well circumscribed parallel hypoechoic bilateral breast masses. She reported receiving the Moderna COVID-19 vaccine 13 days prior.

Case 4: A 57-year-old woman with no personal or family breast cancer history had a single, enlarged prominent left axillary lymph node when she came in for routine screening mammography and ultrasound. Based on her medical records, she received the Pfizer-BioNTech vaccine eight days prior.

Overall, according to data from the Centers for Disease Control & Prevention, 11.6 percent of vaccine recipients experience adenopathy after one dose, and 16 percent do so after the second dose. The enlarged lymph nodes typically appeared within 2-to-4 days post-vaccination. Given the likelihood this side effect will develop in a significant number of patients, radiologists must remember to include it as a potential differential diagnosis, the team said.

“Recognizing this as a potential differential diagnosis is crucial to being able to provide appropriate follow-up recommendations,” they said. “This would, in turn, decrease the number of false-positive axillary lymph node biopsy recommendations, thus minimizing patient harm and costs.”

If these adenopathies do appear, Mehta’s team recommended repeating targeted ultrasound of the affected axilla between 4-to-12 weeks after the patient is scheduled to receive the second dose of the vaccine. For abnormalities that persist, an ultrasound-guided core needle biopsy could be necessary to rule out malignancy.