Fig. 2

Screening mammography performed in a 44-year-old woman with a positive family history for breast cancer (mother and aunt), bearing implants for aesthetic purposes. Mammography (a) was considered negative. Breast ultrasonography was also performed because of her family history and high breast density (ACR category d). While ultrasonography was negative for both breasts, multiple round, enlarged, hypoechoic lymph nodes (measuring up to 1 cm in axial diameter), with a thickened (< 3 mm) cortex, were seen in the left axilla (b). There were no skin changes and there was no history of any infection or trauma. On the right side, axillary lymph nodes were normal. Because of her family history and the presence of breast implants, magnetic resonance imaging was performed (c T2-weighted short-time inversion recovery; d fat-sat contrast-enhanced T1-weighted gradient-echo; e apparent diffusion coefficient map). No suspicious mass or non-mass lesions were seen in both breasts. Implants showed no signs of rupture (not shown). In the left axilla, multiple enlarged lymph nodes were well visible in c and d (red circles); on the apparent diffusion coefficient map (e, red circle), they mainly exhibited low signal (restricted diffusivity). When an ultrasound-guided biopsy of the most suspicious lymph node was proposed, the patient mentioned that she had a Comirnaty COVID-19 vaccination one week before in the left arm. The attending radiologist was more than surprised to hear this, as at that time, a COVID-19 vaccination was only administered to people older than 70 years. Follow-up performed four weeks after the second vaccination was negative and showed no residual enlarged lymph nodes