Fibrosarcoma
A sarcoma in which the predominant cell type is a malignant fibroblast.
In the skull, it appears as a radiolucency or bone defect.
The malignant transformation from a chordoma into fibrosarcoma or malignant fibrous histiocytoma is rare.
The malignant transformation of a fibrous dysplasia occurs in < 1% of cases 1) typically to osteosarcoma, but other sarcomas are possible (fibrosarcoma, chondrosarcoma…)
1)
Lee JS, FitzGibbon EJ, Chen YR, et al. Clinical guidelines for the management of craniofacial fibrous dysplasia. Orphanet J Rare Dis. 2012; 7 Suppl 1:S2–S2