Abstract
Breast osteosarcoma is a rare malignancy of unknown etiology, with no standard adjuvant treatment at present. The prognosis of the disease is poor, and it has a high propensity for recurrence and metastasis. The current report presents the case of a 52-year-old woman, in whom adenomyoepithelioma gradually developed into breast osteosarcoma following three separate surgeries. The patient survived for 41 months from the initial lesion occurrence and resection in the left breast; during this time, she underwent surgery and chemotherapy (liposomal doxorubicin and cisplatin) for the treatment of disease recurrence and lung metastasis, along with molecular-targeted therapy (sunitinib). However, the patient eventually succumbed to respiratory failure due to progressive disease. The present case underwent a clear pathological transformation process, and may provide a basis for an improved understanding of the clinical characteristics and treatment of breast osteosarcoma.