A 59-year-old female reported...a pure mucinous breast carcinoma that was ER (100%, moderate-strong intensity), PR(-), 5% Ki-67 (+), and...HER2 gene was found to be amplified...she received four 21-day cycles of intravenous docetaxel...intravenous cyclophosphamide...and intravenous trastuzumab...a full year of treatment....letrozole daily for 5 years...After following up for 2 years, the patient's outcome was survival without recurrence.