ERBB2 and cancer: This study aimed to evaluate ultrasound viscosity imaging (UVI) for distinguishing benign from malignant breast lesions and noninvasively assessing human epidermal growth factor receptor 2 (HER2) status.<h4>Materials and methods</h4>We conducted a retrospective analysis of 274 breast lesions, randomly divided into a derivation cohort and a validation cohort (VC) at a 7:3 ratio.