Multimodal Imaging Findings Including High-resolution 3D T2-weighted Imaging for COVID-19 Vaccine-associated Axillary Lymphadenopathy in a Patient with Breast Cancer

COVID-19 vaccines have received authorization worldwide. Vaccines are typically administered to the deltoid muscle, and axillary swelling/tenderness at the first dose (11.6%) and the second dose (16%) have been reported as secondary effects. Regional lymphadenopathy in the axilla and supraclavicular region has also been reported with a prevalence of 1.1% and is referred to as COVID-19 vaccine-associated lymphadenopathy (VAL). COVID-19 VAL mimics lymph node (LN) metastases on magnetic resonance imaging, ultrasound, and 18F-fluoro-2-deoxy-Dglucose positron emission tomography. Although several specific findings of VAL on clinical imaging have been reported, the difficulty in differentiating between VAL and LN metastases could lead to false-positive or -negative diagnoses. Here, we report a case of breast cancer with ipsilateral VAL with multimodal imaging including 3D T2-weighted imaging, a new magnetic resonance imaging technique, and discuss the future perspective for differentiating between VAL and LN metastases.