VALUE OF IMMUNOHISTOCHEMICAL DETECTION OF NONCOLLAGENOUS PROTEINS OF BONE FOR THE DIAGNOSIS OF BONE-TUMORS

The expression of osteonectin, osteopontin, bone sialoprotein, and ost eocalcin was evaluated by immunohistochemistry in 57 cases of osteoid- forming and non-osteoid-forming bone tumours using specific polyclonal antibodies and the avidin-biotin peroxidase complex method. A positiv e immunostaining was found in all of the osteoid-forming rumours (oste oblastoma and osteosarcoma), both in the cells and in the extracellula r matrix. Among non-osteoid-forming tumours, immunoreactivity to nonco llagenous proteins was present in the cells but not in the matrix of c hondrosarcoma, malignant fibrous histiocytoma, and fibrosarcoma, as we ll as in the mononuclear component of giant-cell rumours. Contrary to small-cell osteosarcoma, Ewing's sarcoma was always negative for all o f the noncollagenous proteins considered. These results suggest that t he immunohistochemical evaluation of noncollagenous proteins of bone m ay be a useful tool for the differential diagnosis of bone neoplasms, particularly among the heterogeneous group of small round cell tumours .