Giant Cell-Rich Osteosarcoma.

Giant cell–rich osteosarcoma makes up about 3% of all osteosarcomas. Histologically, giant cell–rich osteosarcomas are characterized by an abundance of osteoclast-like giant cells and a paucity of tumor osteoid and bone. The histologic appearance can be similar to giant cell tumor.

This paucity of tumor osteoid results in imaging features unlike those of conventional osteosarcomas. In addition, differentiation from benign lesions can sometimes be difficult. Giant cell–rich osteosarcomas are usually lytic and have poorly defined borders. Periosteal reaction is scant or absent and a soft tissue mass is usually not present.

The biological behavior is not necessarily different from that of conventional osteosarcoma.

References

• Bathurst N, Sanerkin N, Watt I. Osteoclast-rich osteosarcoma. Br J Radiol. 1986 Jul;59(703):667-73.