Maxillary malignant mesenchymoma and massive fibrous dysplasia.

This is the first report (to our knowledge) that describes a patient with massive polyostotic fibrous dysplasia involving the calvaria and facial skeleton that subsequently underwent transformation to a malignant mesenchymoma with elements of chondrosarcoma, osteosarcoma, and rhabdomyosarcoma arising in the maxilla. Malignant transformation occurred in the absence of prior radiation exposure, osteomyelitis, or known bony infarction. A review of the literature did not reveal any similar cases of massive fibrous dysplasia of the maxilla degenerating to multiple simultaneous malignant histotypes.