Axillary adenopathy after COVID-19 vaccine in patients undergoing breast ultrasound.

After COVID-19 vaccination, a spectrum of axillary lymphadenopathy were observed in patients undergoing routine breast ultrasound. Malignancy remains the most serious differential in cases of unilateral axillary adenopathy. Knowledge of axillary ultrasound findings after COVID-19 vaccination is essential to prevent unnecessary biopsy or change in therapy in oncological patients. From March to May 2021, 10 female patients underwent breast ultrasound in our Department for the evaluation of axillary lumps. All the patients received their first or second dose of COVID-19 vaccine 20-30 days before the exam in the same extremity of the ultrasound evaluation where lymphadenopathy was found. Five patients had a personal history of previous breast cancer, and the radiologist decided to perform a core biopsy (the histology was negative for malignancy). The other five patients with no personal history of cancer underwent ultrasound and returned after a short-term follow-up. Regression of the enlarged lymph nodes was found.