ESR1 and ductal breast carcinoma in situ: Compared to DCIS, MIBC is seen in association with high nuclear grades, necrosis, human epidermal growth factor receptor 2 (HER-2) positivity and a high Ki-67 positivity index, whereas the rates of estrogen receptor (ER) and progesterone receptor (PR) positivity are lower in patients with microinvasive carcinoma arising the background of extensive DCIS12.