A case of breast cancer metastatic to the tail of the pancreas.

Breast cancer metastasis to pancreas is rarely seen. There have been only 6 cases described in the literature. We present the seventh case of a 54-year-old woman with breast cancer that metastasized to the tail of the pancreas 4 years and 4 months after radical mastectomy. Although the serum levels of CA15-3 and TPA had gradually increased without symptoms, it was difficult to establish the diagnosis before contrast-enhanced abdominal CT scan was performed. Immunohistochemical staining using E-cadherin was positive, proving that the breast cancer was ductal rather than lobular in origin. CA15-3 immunohistochemically stained positive in the resected pancreas lesion. Positive monoclonal staining by GCDFP-15 (gross cystic disease fluid protein-15) in the pancreas tumor also confirmed it breast cancer origin. Investigation of chemokine/chemokine receptors may clarify a new mechanism of metastasis to the pancreas from breast cancer.