Cellular heterogeneity in giant cell tumour of bone (osteoclastoma): an immunohistological study of 16 cases.

Sixteen cases of giant cell tumour of bone (osteoclastoma) were analysed by immunohistochemical techniques using various monoclonal antibodies specific for macrophages, monocytic and granulocytic cells, T- and B-lymphocytes and other cell types. The multinucleate osteoclastic giant cells failed to react with the majority of antibodies specific for myeloid cells and HLA-DR. In contrast to previous findings, giant cells in some tumours reacted with a rat, but not mouse, antibody to leucocyte common (CD45) antigen. Macrophages were detected in all tumours, though their numbers varied considerably; small numbers of T- and B-lymphocytes were identified in four of 16 cases. The neoplastic, spindle-shaped, stromal cells were largely unreactive with the monoclonal antibodies used in this study, further supporting the view that they are not the precursors of the characteristic giant cells, nor are they of haemopoietic origin.