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 m ainly in the jaws. The giant cell tumour (GCT) is a benign locally aggressi ve neoplasm located near the articular end of tubular bones. Both lesions a re characterised histologically by multinucleated giant cells in a backgrou nd 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 clarifi ng such question. The expression of these proteins is also important to det ermine 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 p5 3 immunoreactivity, all the samples showed wide expression of MDM2. The per centage 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 ac tivity compared with that of the GCT. Our results also suggest that p53 ina ctivation by MDM2 expression may be involved in the pathogenesis of giant c ell lesions of the jaws and long bones.