Invasive micropapillary
carcinoma (IMPC) is a novel type of
breast cancer which is potentially very aggressive and may show early lymphatic infiltration.
Monosomy of chromosome 17 (m17) is rare in
breast cancer, and according to the 2018 guidelines of the American Society of Clinical Oncology/College of American Pathologists, the decision to administer
trastuzumab treatment should be made based on positive
human epidermal growth factor receptor 2 results by immunohistochemistry. Here, we report a rare case of bilateral local advanced IMPC involving m17. A 33-year-old woman found a mass measuring 30 mm on the left breast that increased to 100 mm over 3 months. A diagnosis of IMPC was made based on the findings of core needle biopsies of bilateral breast masses and left axillary lymph node, and m17 was detected by fluorescence in situ hybridization (FISH). The patient underwent 6 cycles of
neoadjuvant chemotherapy (
docetaxel,
epirubicin, and
cyclophosphamide) and left-side
modified radical mastectomy, left axillary
lymph node dissection, right
breast-conserving surgery, and right sentinel lymph node biopsy. Postoperative pathologic analysis of both breasts revealed IMPC, and m17 was confirmed by FISH. The patient received
radiotherapy and endocrine
therapy but rejected
trastuzumab treatment. The patient was still alive at the 30-month follow-up, without recurrence or
metastasis. Our findings suggest that loss of chromosome 17 may influence prognosis or therapeutic response, which needs to be further confirmed.