Abstract
BACKGROUND: Lung cancer rarely metastasizes to the breast, and breast metastasis of pulmonary pleomorphic carcinoma has not been previously reported. CASE PRESENTATION: The patient was a 66-year-old woman who became aware of a mass in the right breast and visited a physician. She was referred to our department for close examination, upon which she was diagnosed with double cancer (right breast cancer and left lung cancer). Needle biopsy findings for the mammary tumor were similar to those for the lung biopsy specimen, but spindle cell or metaplastic carcinoma were possibilities. The initial diagnosis was primary breast cancer. Left upper lobectomy and lymph node dissection were performed for left lung cancer. Both the lung and mammary tumors grew rapidly during the wait for surgery. The white blood cell count was within the normal range at the first examination, but was markedly increased and remained at a high level after surgery for lung cancer. Preoperative chemotherapy was initially planned for the mammary tumor, but surgical treatment was selected in consideration of the clinical course, and right mastectomy and full thickness skin graft were performed. However, the disease rapidly aggravated and the patient died 5 months after the first examination. CONCLUSION: The final diagnosis was pulmonary pleomorphic carcinoma with metastasis to the breast on postoperative histopathological examination. We describe this case as the first reported example of breast metastasis of pulmonary pleomorphic carcinoma.