periosteal osteosarcoma
per·i·os·te·al os·te·o·sar·co·ma
periosteal osteosarcoma
An uncommon (less than 2%) osteosarcoma (OS) with the same demographic as conventional OS. It is related to periosteal chondrosarcoma, and usually arises in diaphysis of the proximal tibia or distal femur.Imaging
Small radiolucencies on bone surface with bone spicules perpendicular to shaft and penetrating soft tissues; no medullary involvement.
DiffDx
Parosteal chondrosarcoma—lobules of malignant cartilage with calcification and surface endochondral ossification, no malignant osteoid.
Genetics
Usually diploid.
Prognosis
Intermediate between high-grade and parosteal (juxtacortical) OSs or chondrosarcoma; high local recurrence; 15% metastasise.