Several studies in the literature have demonstrated the usefulness of CEUS in differentiating benign and malignant breast lesions, evaluating pathological characteristics of breast cancer (estrogen and progesterone receptors, histological grade, human epidermal growth factor receptor 2, Ki-67), detecting the sentinel lymph node and even predicting the response to neoadjuvant chemotherapy (NAC) [1,2,3,4]. This evidence concerns the gene MKI67 and breast cancer.