Primary Chondroblastic Osteosarcoma of the Breast in a Teenager: What Is Changing?

Abstract

Abstract Background Nonepithelial tumors of the breast are extremely rare and have an incidence of less than 1%. The most common nonepithelial breast tumor is phyllodes tumor (PT), which accounts for 61%. Primary osteosarcomas of the breast contribute up to only 12.5% of all the extraosseous osteosarcomas, and among young females, they are extremely rare, especially in those without a previous history of primary bone osteosarcoma. A case of a 16-year-old female with primary chondroblastic osteosarcoma of the left breast is herein presented. Case Description In this report, we describe and report a 16-year-old female with neither a previous history of bone osteosarcoma nor a family history of breast cancer who was diagnosed with a primary chondroblastic osteosarcoma of the left breast. The mass was shining, warm, firm, and slightly fixed. The excisional biopsy showed a large tumor measuring 11 × 9 × 7 cm, encapsulated, grayish-white, and nodular. The H&E-stained sections showed a tumor composed of atypical spindle cells, large pleomorphic epithelioid cells, and multinucleated cells of osteoclastic type with osteoid formation with abundant areas having malignant chondroid matrix. About 40 atypical mitoses/10 HPF were seen. A diagnosis of primary osteosarcoma was made. Immunohistochemically, the tumor was triple negative, vimentin was strongly positive, SMA was focally positive, and AE1/AE3 was negative. The patient was put under observation. Her postoperative course is generally promising without any complaint of pain. We present a case of a very young female with the rarest diagnosis of primary osteosarcoma involving the left breast. Conclusion Primary osteosarcomas of the breast carry poor prognosis by being triple negative, and because of being the rarest tumors, they pose a challenge in managing the patients due to lack of established treatment modalities.