An immunohistological study of giant‐cell tumour of bone: Evidence for an osteoclast origin of the giant cells

Using a panel of monoclonal antibodies against a variety of lymphoid and non-lymphoid antigens the immunohistological staining pattern of giant cells from a case of giant-cell tumour of bone has been compared with that of osteoclasts from the developing ends of fetal long bones. Only EBM-11, an antibody reacting with a wide spectrum of macrophages, stained both osteoclasts and giant cells; stromal cells and osteoblasts did not react. This indicates that osteoclasts and giant cells are phenotypically and presumably functionally similar. It is argued that the osteoclasts and the tumour-derived giant cells in bone are derived from a similar mononuclear precursor.