Mucinous carcinoma of breast is a rare variant of invasive breast carcinoma and usually affects older females and is associated with good prognosis. Human epidermal growth factor receptor 2 (HER2) positivity in these tumors is rare. We describe here a case of advanced stage HER2 + mucinous carcinoma with micropapillary features who underwent complete remission on treatment with radiation therapy and hormonal therapy and presented after eight years with invasive duct carcinoma in the contralateral breast.
