Abstract
A 68-year-old woman presented with a history of hemoptysis. She had been receiving hormone therapy and chemotherapy for recurrent breast cancer. She was diagnosed with diffuse alveolar hemorrhage caused by metastatic breast cancer, as evidenced by increasingly bloody bronchoalveolar lavage fluid and malignant cells in multiple lung lobes. This condition was associated with tumor emboli in the pulmonary vasculature and transformation into a hormone receptor-negative state. Serial changes in chest computed tomography findings, from diffuse patchy ground-glass opacities to multiple nodules, are notable. This rare mode of metastasis may be associated with a poor prognosis.