A 39-year-old woman with recently diagnosed ductal carcinoma in situ in the right breast but no palpable axillary lymphadenopathy underwent MRI to evaluate the extent of disease; the day before MRI, she received a second dose of mRNA COVID-19 vaccine in her right arm. MRI revealed edema surrounding 2 enlarged, morphologically abnormal level-1 axillary lymph nodes and an irregular mass with irregular margins. What is the diagnosis and what would you do next?
Source: JAMA Online First