Metastases to breast from primary lung cancer

Metastatic disease to the breast from extra mammary sites is uncommon and has an incidence of 0.5 to 3%. It is important to make an accurate diagnosis as this has an impact on the therapeutic planning and management. Clinically, it can be difficult to differentiate between primary breast cancer and a metastatic disease. An incorrect diagnosis can lead to unnecessary surgical interventions. Immunohistochemistry has a significant role in identifying the primary origin of tumor and has to be considered in the presence of unusual cytologic patterns. We report three cases of metastatic disease to breast from primary lung tumors. The cases demonstrate the difficulties encountered in the diagnosis and the impact on the management of these patients.