Immunohistochemical expression of p53, MDM2, Ki-67 and PCNA in central giant cell granuloma and giant cell tumor.

Central giant cell granuloma (CGCG) is a reactive bone lesion that occurs mainly in the jaws. The giant cell tumour (GCT) is a benign locally aggressive neoplasm located near the articular end of tubular bones. Both lesions are characterised histologically by multinucleated giant cells in a background of ovoid to spindle-shaped mesenchymal cells. There is a basic question whether both lesions are separate entities or variants of the same disease. The study of cell cycle-associated proteins may give insights into clarifying such question. The expression of these proteins is also important to determine the cell cycle regulation in both tumours. The purpose of this study was to evaluate the immunohistochemical expression of p53, MDM2, Ki-67 and PCNA in CGCG and GCT. The results demonstrated that, despite the lack of p53 immunoreactivity, all the samples showed wide expression of MDM2. The percentage of Ki-67- and PCNA-positive cells in CGCG was statistically higher than that of GCT Our findings show that CGCG has a higher proliferative activity compared with that of the GCT. Our results also suggest that p53 inactivation by MDM2 expression may be involved in the pathogenesis of giant cell lesions of the jaws and long bones.