Coronavirus disease 2019 (COVID-19) vaccination-induced unilateral axillary lymphadenopathy: case series with follow-up and literature review

Multiple studies have reported on unilateral axillary adenopathy following coronavirus disease 2019 (COVID-19) vaccination, which is currently recognized as a common finding. Here, we present a series of eight adult patients with reactive axillary lymphadenopathy following COVID-19 vaccination, in whom the follow-up ultrasonography (US) showed resolution of a previously noted unilateral axillary adenopathy. From March 2021 to March 2022, 2,599 consecutive women underwent breast US in Jeju National University Hospital. We identified 10 patients with unilateral axillary lymphadenopathy following COVID-19 vaccination detected on the breast US. The 10 patients were recommended for follow-up US. Two patients were lost to follow-up, whereas the remaining eight patients underwent follow-up US, in whom resolution of the unilateral axillary lymphadenopathy was noted. Radiologists should be aware of evolving guidelines for evaluating and managing axillary lymphadenopathy to avoid false positive biopsies. Recent studies on lymphadenopathy following COVID-19 vaccination show that a prolonged duration until resolution is often observed. Therefore, a follow-up US examination at least 12 weeks after vaccination may be reasonable. Furthermore, management guidelines should include a risk-stratified approach considering both vaccination timing and the patient’s overall risk of metastatic disease.