Abstract
Primary osteosarcomas of the breast are extremely uncommon. Here we describe a case of a 77-year-old woman who presented with a hard mass on her right breast. Mammography and breast ultrasound demonstrated a round-shaped calcified mass on the right breast but the features were not definitely diagnostic. For diagnostic purposes, an excisional biopsy was performed and the mass proved to be a primary osteosarcoma of the breast by pathologic findings. PET-CT and whole body bone scan showed neither evidence of metastasis nor underlying bone lesions. Wide excision without axillary lymph node dissection was performed after diagnosis. Further treatment such as adjuvant chemotherapy or radiation therapy was not performed. We discuss proper treatment of this rare type of breast cancer.