A Very rare case report of male invasive micropapillary breast carcinoma in China and review of literature

Introduction: To report a rare case of male breast micropapillary carcinoma (MBMC) with early metastasis of axillary lymph nodes, the molecular characteristics were further studied in both primary and metastatic foci. In addition, we have reviewed similar published cases in the literature and tried to outline the molecular charac-teristics of this disease.Presentation of case: A 63-year-old male patient presented with a painless mass on the medial side of left breast and was pathologically diagnosed with MBMC. Postoperative examination revealed 80 % invasive ductal car-cinoma (IDC) and 20 % invasive micropapillary carcinoma (IMPC) in the mass, with a histological grade WHO III. There were 25 axillary lymph nodes, 11 of which were metastatic, including 5 macrometastasis and 1 micrometastasis, with a lymph node metastasis rate of 44 % (11/25). Pathological TNM stage: pT2N2M0. Immunohistochemical results in primary foci: AR (90 %, +), HER-2 (1 +) and ER (90 %, +), PR (60 %, +), E -cadherin (+), EGFR (-), GATA -3 (90 %, 3 +), Ki -67 (50 %). Lymph node metastasis: AR (40 %, strong +), HER -2 (2+), ER (90 %, strong +), PR (40 %, strong +), Ki-67 (50 %). AR and Ki-67 were obviously expressed in both primary and metastatic foci. A mixture of IDC and IMPC was found in lymph node metastases, both of which expressed varying degrees of AR and Ki-67.Clinical discussion: MBMC is easy to early metastasized to lymph node. In this case, there was no significant difference between primary and metastatic cancer in molecular results. It is positive for ER and PR, but negative for HER-2 in this patient. There is few data on male HER-2 expression, HER-2 expression is deficient in this case. AR is found to be positive in 50 % of MBMC cases, although their clinical relevance has not been established yet. The significance of EGFR in the prognosis of MBMC remains unclear, however, EGFR positive expression is not found in this patient.Conclusions: MBMC is a rare disease characterized by early lymph node metastasis, high histological grade, positive ER and PR, and generally negative HER-2. The molecular biological characteristics and prognostic significance of MBMC need to be further studied in order to develop the optimal treatment strategy.