For the past six weeks, there has been a collective sigh of relief in the UK and USA as vaccines for Covid-19 have been rolled out. With the virus still surging in both countries – the UK has just recorded 100,000 deaths while in the USA the death toll is approaching half a million – the vaccines from Pfizer-BioNTech and Moderna have arrived not a moment too soon. However, an important paper out of New York has just been published in Clinical Imaging, highlighting one of the side effects of the vaccine for women aged between 40 and 60.
The authors, who are radiologists affiliated with the Weill Medical College of Cornell University, summarised four case studies of women who presented with swollen lymph nodes in the axillary region (i.e., armpit). When taking the patients’ histories, the clinicians discovered that each woman had recently received a vaccination in the ipsilateral upper extremity and deduced that the aetiology for the lesion – a hyperplastic adenopathy – was the vaccine itself. All four patients had normal mammograms, but hand-held ultrasound (HHUS) examination revealed lesions that appeared to mimic breast malignancies.
Case number 4 was a 57-year-old woman with no personal or family history of breast cancer who attended the clinic for routine breast screening examination, consisting of full-field digital mammography (FFDM) followed by HHUS. Her medical record stated that she had received the Pfizer vaccine in her left arm 8 days prior to her visit. Her mammograms were unremarkable, while the ultrasound image for her left side showed an enlarged axillary lymph node with diffuse cortical thickening (seen left, © Elsevier). As seen below right, no abnormal lymph nodes were detected on her contralateral (i.e., right) side.
The authors commented: “As the differential diagnosis of unilateral axillary adenopathy includes breast malignancies, it is crucial to thoroughly evaluate the breast and to elicit history of recent vaccinations. This would decrease the number of false-positive biopsy recommendations, thus minimizing patient harm and cost.” They continued, “We recommend repeat targeted ultrasound of the affected axilla 4 to 12 weeks after the patient’s scheduled second vaccination dose to ensure resolution.”
The administration of a vaccine elicits a strong immune response and as established with other vaccines for smallpox, human papillomavirus and H1N1 influenza, can lead to enlarged axillary nymph nodes. In a few well documented cases, patients’ recent vaccination history was overlooked which led to the misdiagnosis of malignancy. Given the importance of these findings on the Covid-19 vaccines, the Society of Breast Imaging has recently published management guidelines for radiologists.