Malignant Giant Cell Tumor of Bone: A Study of Clinical, Pathological, and Prognostic Profile from One Single Center.

Malignant giant cell tumor of bone (GCTB) is a rare malignant bone tumor. This analysis was conducted on patients with malignant GCTB at our center. The clinical, demographic, and prognostic characteristics were evaluated and compared. During 1 January 2015 to 31 December 2022, fifty patients were included in the study, which made up 3.3% of the contemporary GCTB patients. The clinical characteristics were comparable between the 24 patients with primary malignant GCTB (PMGCTB) and 26 patients with secondary malignant GCTB (SMGTCB). The tumor location was mainly at the axial and pelvic region (70%) and differed between the two types (p = 0.040). H3F3A pathogenic variant presented frequently in SMGCTB (p = 0.020). Cox regression analysis showed the prognostic outcomes were poor in those with a tumor located in the axial bone and sacrum with invasion of other places. H3F3A mutation status is also a risk factor, while chemotherapy and denosumab failed to demonstrate prognostic benefits. Malignant GCTB is a rare condition with a poor prognosis, especially in SMGTCB. The location and H3F3A mutation status had an influence on prognosis, and systemic therapy should be taken into consideration for patients with unfavorable prognostic features.