| Giant cell tumor (GCT) of long bone and central giant cell granuloma (CGCG) of the jaw show similar microscopic features. These tumors can show high proliferative activity suggesting deregulation of the cell cycle control. Therefore, they were assessed for the presence of cyclin D1 gene amplification and protein overexpression and for the expression of cyclin B1 and the proliferation-associated antigen Ki-67. Low level cyclin D1 gene amplification was detected in 61% of GCT and 31% of CGCG. Almost all cases showed cyclin D1 protein overexpression in the giant cells. Cyclin B1 and Ki-67 staining was restricted to the mononuclear cells with no staining present in the giant cells. Cyclin D1 regulation is abnormal in both GCT and CGCG. This supports the possibility that GCT and CGCG are similar diseases and that the clinical and histological differences noted between these two entities maybe due to differences in the anatomical site of involvement. |
