Introduction Patients undergoing complete treatments of breast carcinoma can be found with pulmonary nodules during the follow up period. Either metastasis from breast carcinoma or second primary bronchogenic carcinoma should be considered as a possible diagnosis. Case presentations Two female patients with ages of 66 and 64, underwent modified radical mastectomy for breast carcinoma 5 and 2 years ago, were found with single pulmonary nodule, 1.0 cm and 0.8 cm from the left lower and right upper lobe. There was no other site of metastasis being noted after systemic survey. Wedge resections through video assisted thoracic surgery were performed and one of them underwent lobectomy and mediastinal lymph node dissection after the primary lung carcinoma being proved pathologically (thyroid transcription factor 1 and cytokeratin 7 positive). The dissected lymph node in this patient is negative for malignancy. They underwent low dose chemotherapy postoperatively because of increased risk of tumor occurrence for these patients. Patients with smoking or irradiation history usually favor the diagnosis of second primary lung carcinoma. However, these two treated breast carcinoma cases, which didn’t have smoking or irradiation history, developed second primary lung carcinomas. It is relatively rare reported before. Conclusions Pulmonary nodules in patients with prior breast carcinomas were usually regarded as metastatic lesions. However, the possibility of second primary still cannot be excluded, especially to the solitary type. Video assisted thoracic surgery can provide early and accurate diagnosis as well as effective treatment.