History A 25-year-old woman was referred to our breast clinic for assessment of a palpable mass in her left breast that developed quickly in 2 weeks. She denied any associated fever, chills, redness, or pain. She had no relevant medical or surgical history; no evidence of recent pregnancy, abortion, or breastfeeding; and no family history of breast cancer. Clinical examination enabled confirmation of a firm mass occupying the retroareolar region and the outer quadrant of the left breast with no skin retraction, edema, or erythema. There was no evidence of enlarged axillary lymph nodes. US of the left breast (Fig 1), bilateral breast MRI (Fig 2), and fluorine 18 fluorodeoxyglucose PET/CT (Fig 3) were performed.