Clear-cell chondrosarcoma: a report of five cases including ultrastructural study.

Five cases of clear-cell variant of chondrosarcoma (Unni et al.) are reported. The tumors occurred in the epiphyseal region of long bones; three in the femoral head. Roentgenographically, the lesion was usually a well-defined and benign appearing one, either purely lytic (3 cases) or with central radiodensity (2 cases). Histologically, all five cases had areas of conventional chondrosarcoma; however, the greater portion of the tumor was made up of sheets of clear-cells intermixed with nonneoplastic bone trabeculae but devoid of chondroid matrix. Electron microscopic studies showed that these clear-cells possess cytoplasmic microvilli, abundant glycogen particles and prominent golgi complexes, like normal or tumorous chondroid cells usually have. In our experience, the best treatment seemed to be en bloc resection with joint replacement; indeed, despite the fact that they are true chondrosarcomas, these tumors usually have a very slow rate of growth.