Abstract

Background: The histopathological features of osteosarcoma after neoadjuvant chemotherapy are not fully characterized, and there is still a lack of standardized evaluation criteria. This study aimed to assess the histopathological features of osteosarcoma after chemotherapy and to evaluate their associations with clinical and imaging factors, in order to help optimize limb-salvage strategies. Objective: To investigate the histopathological features of osteosarcoma after neoadjuvant chemotherapy and their associations with clinical and imaging characteristics to optimize limb-salvage strategies. Materials and Methods: We included 34 cases of osteosarcoma treated with neoadjuvant chemotherapy followed by limb-salvage surgery at Musculoskeletal Diseases and Oncology Department, Hospital for Trauma and Orthopedics of Ho Chi Minh City from October 2024 to March 2026. Results: The mean age was 18.4 ± 10 years. Males accounted for 55.9% of cases. Most tumors were located in the “proximal the knee, distal from the elbow” region (88.2%). On radiographs, periosteal reaction was the most common finding (91.2%). The concordance rate between histological subtypes identified in biopsy and surgical specimens was 76.5%, with the osteoblastic subtype being the most common. A good response to chemotherapy (Huvos grades III, IV) was observed in 55.9% of cases. Abnormal mitotic figures and vascular invasion identified in surgical specimens were significantly associated with a poor response to neoadjuvant chemotherapy (p < 0.05). The number of osteoclasts in a biopsy specimen was significantly associated with a favorable response to chemotherapy and negative surgical margins (p < 0.05). Conclusion: The number of osteoclasts in a biopsy specimen, abnormal mitotic figures, and vascular invasion were associated with the response to neoadjuvant chemotherapy and surgical margin status. In contrast, the histological subtypes of osteosarcoma showed no statistically significant association with these parameters.