MDM2 and osteosarcoma: Its bland histological appearance can lead to misdiagnosis or underdiagnosis, and no standardized treatment protocols have been established for this disease.<h4>Conclusion</h4>Core needle biopsy of radiation-induced low-grade osteosarcoma of the breast is prone to misdiagnosis due to limited sampling and bland histological morphology; comprehensive pathological evaluation of surgical specimens combined with a specific immunohistochemical panel (SATB2, MDM2, β-catenin) is key to a definitive diagnosis.