Periosteal mesenchymal chondrosarcoma of the tibia with multifocal bone metastases: a case report.

Mesenchymal chondrosarcoma of bone is a rare high-grade variant of chondrosarcoma, which typically has central intramedullary location. The tumor is characterized by admixture of highly anaplastic small round malignant cells and islands of mineralized low-grade hyaline cartilage. It is most unusual for this tumor to arise on the surface of a long bone. We describe a patient with periosteal mesenchymal chondrosarcoma that arose at the surface of the right tibia with multifocal bone metastases. Radiographic, CT, MRI, and PET-CT features of this unusual tumor are presented.