COVID-19 vaccination-related unilateral lymphadenopathy: Lymphadenopathy awareness after COVID-19 vaccinations

Abstract

A woman in her 30s working at a hospital was admitted to our hospital for a routine follow-up checkup and medication, as she had undergone right skin-sparing mastectomy and breast reconstruction at another hospital. The sonography at the time of the checkup showed two 10-mm infraclavicular lymphadenopathies with uniformly diffuse thickened cortices and fatty hila. As the patient had received her second dose of the COVID-19 vaccine in her left deltoid muscle 4 weeks prior to the test, the infraclavicular lymphadenopathies were considered as representing benign reactive lymph node enlargement in response to the COVID-19 vaccination. The lymphadenopathy was shrinking in a repeat sonography performed 12 weeks after the second dose of the vaccine. With the mass rollout of COVID-19 vaccinations, COVID-19 vaccination-related unilateral lymphadenopathy has become an important clinical condition to be recognized by clinicians, patients, and the general population. The lymphadenopathy is visible on imaging as early as 1 day after the vaccination, and in some cases, persists for more than 10 weeks after the vaccination. Therefore, imaging tests for non-urgent indications, such as screening mammography, should be scheduled prior to vaccination or be postponed to at least 6 weeks after the final vaccine dose; however, imaging tests for urgent clinical indications, such as treatment planning, active treatment monitoring, and assessment of new symptoms should not be delayed, irrespective of the vaccination status. An additional strategy to mitigate confounding findings would be to administer the COVID-19 vaccine on the side contralateral to the primary cancer (in patients with/with a history of cancer) or in the thigh. Ipsilateral lymphadenopathy following COVID-19 vaccination in the previous 6 weeks may be considered as being benign, and further imaging is not indicated. However, clinical management is recommended, with ultrasonographic examination, if the concern persists later than 6 weeks after the final vaccine dose. Recording of the vaccination status (date[s] of vaccination[s] and injection site [left or right, arm or thigh]) for all patients presenting for imaging and having that information readily available to the radiologist and physician at the time of interpretation can reduce unnecessary return visits by the patient and/or delays in the final assessment. Widespread patient education regarding COVID-19 vaccination-related unilateral lymphadenopathy is also needed, especially as this condition may be mistaken as a sign of malignancy. Imaging societies, clinicians, and news media outlets should spread awareness and educate the public about this clinical condition to minimize patient anxiety. At the time of vaccination, the possible development of axillary swelling should be highlighted, and the subjects should be informed that it is part of the normal immune response elicited by the vaccine. Patients also should be aware of the best times to schedule routine screening mammography after COVID-19 vaccination.