ESR1 and breast cancer: The fact that the previously validated POU2F3-positive/KIT-high/BCL2-high tuft cell-like breast cancers were accompanied by POU2F3-positive DCIS components is strongly reminiscent of HER2 + /HR + , as well as the luminal-type ER + , breast cancers in which invasive and in situ components also share the respective IHC hallmarks [27].