Breast as an unusual site of metastasis- series of 3 cases and review of literature.

Background and objectives Metastasis to the breast from extra mammary sites is uncommon with an incidence ranging from 1.2 to 2 % in clinical reports. Approximately 300 cases of breast metastasis from extra mammary sites have been reported, mostly in small series or as a single case report. Gastrointestinal adenocarcinoma metastasising to the breast is also very rare and only 30 cases have been reported in the literature. Metastatic deposits within the breast may be difficult to distinguish from primary breast carcinoma. Radiological features and immunohistochemistry especially for steroid hormone receptors (ER/PR) and expression of gross cystic disease fluid protein (GCDFP) and presence of other immunohistochemistry protein factors in breast metastasis which are specific to primary site may be helpful in differentiating these two conditions. Materials and methods In this series of 3 cases of breast as an unusual site of metastasis, we present different cases of adenocarcinoma of stomach, sigmoid colon and kidney with metastasis to the breast and discuss the differential diagnosis and management plans. Conclusion In conclusion, secondary tumors to the breast are rare and thus differentiating primary tumors from metastatic breast carcinoma is important for rational and optimum therapy and avoidance of unnecessary radical surgery. Palpable breast lump without typical radiological signs of primary breast carcinoma in patients with known primary should be suspected of representing metastasis.