Primary osteosarcoma of the breast with abundant chondroid matrix and fibroblasts has a good prognosis: A case report and review of the literature.

The present study describes the case of a 77-year-old female with a recently self-detected, painless, 7-cm lump in the left breast, without evidence of metastasis clinically, who underwent mastectomy with dissection of the axillary lymph nodes. The tumor did not invade the chest wall and skin. The tumor was comprised of abundant chondroid matrix and fibrous tissue, with focal osteoid matrix, and was classified as a chondroblastic/fibroblastic variant. The tumor had a reverse zonal pattern. The tumor cells in the central portion were mainly spindle-like and sparse with minimal cytological atypia, while the remaining tumor cells in the periphery were mainly epithelioid, atypical and dense. Neoplastic osteoid woven bone or trabeculae were observed in the central portion of the tumor. No metastasis was identified in the axillary lymph nodes. The patient was alive without evidence of local recurrence or hematogenous spread at the 60-month follow-up.