Breast metastasis from lung cancer: report of two cases of adenocarcinoma with different gene mutation and one case of squamous cell carcinoma

Breast metastasis from extra-mammary malignancy is not common. According to the literature, an incidence of 0.4-1.3% has been reported. We present three cases of metastasis to the breast from two pulmonary adenocarcinoma and one lung squamous carcinoma diagnosed concomitantly or metachronous with the primary tumor. Two pulmonary adenocarcinomas (a 43-year-old female and a 45-year old female) presented with cough and a massive was found on a chest radiograph. One lung squamous carcinoma of a 75-year old male with no clinical symptom and a massive was found on a chest radiograph accidental. Additionally, on physical examination a poorly defined mass was noted in right breast of the three patients. The patient underwent bronchoscopy, excisional breast biopsy and medical thoracoscopy. By cytology, histology and immunohistochemistry primary lung cancer with metastasis to the breast was diagnosed. From our results, we speculate that lung cancer metastasis to the right side of the breast is more than the left side and the mutations should be detected of the breast adenocarcinoma from lung. Both the primary and metastatic anatomic sites demonstrated histologically extensive solid component of the two pulmonary adenocarcinoma patients.