Giant cell tumour of bone: morphological, biological and histogenetical aspects.

The giant cell tumour of bone (GCT) is a locally aggressive intraosseous neoplasm of obscure biological behaviour. Although well defined in clinical, radiological and histological terms, detailed information on its biological development is still relatively incomplete. The tumoral tissue consists of three cell types--the neoplastic giant cell tumour stromal cells (GCTSC), representing the proliferative fraction, secondarily recruited mononuclear histiocytic cells (MNHC) and multinuclear giant cells (MNGC). These cellular components interact together with factors that have a role in regulating osteoclast function in normal bone tissue (e.g. RANK, RANKL, OPG, M-CSF). Recent publications suggest that the neoplastic stromal cells express differentiation features of mesenchymal stem cells. Further research of the pathogenesis of GCT as well as the complex interactions of its cellular populations may provide the knowledge necessary for developing approaches for a biological-based therapy of this neoplasm.