Mammaglobin, a valuable diagnostic marker for metastatic breast carcinoma

Identification of metastasis and occult micrometastases of breast cancer demands sensitive and specific diagnostic markers. In this study, we assessed the utility of a mouse monoclonal antibody to human mammaglobin for one such purpose. Immunohistochemical stains were performed on paraffin-embedded sections from a total of 284 cases, which consisted of primary breast invasive carcinomas (41 cases) with matched metastases to ipsilateral axillary lymph nodes, metastatic breast carcinoma to liver (1 case) and kidney (1 case), non-breast neoplasms (161 cases), and normal human tissues (39 cases). The results showed 31 of the 41 cases of primary breast cancer with axillary lymph node metastases were positive for mammaglobin (76%). In the meantime, we documented expression of mammaglobin in occasional cases of endometrial carcinoma (17%). Our data further validated that mammaglobin is a valuable diagnostic marker for metastatic carcinoma of breast origin, although endometrial carcinoma should be considered as a major differential diagnosis.