Ag-NORs in giant cell tumor of bones: are they useful in the estimation of tumor's behavior?

: The number of nucleolar organizer regions (NORs) in giant cell tumors of bones was measured using the one-step silver staining technique (AgNOR) with black and white photographs and semiautomatic image analysis. The purpose of the study was to determine whether this method provides useful information on the biological behavior of bone GCTs. The number of AgNORS in bone CGTs (mononuclear cells: 3.45 +/- 1.17, and multinucleate cells: 2.52 +/- 0.97) was found to be higher than in NOF cells (2.16 +/- 1.02 and 2.01 +/- 0.78) but lower than in MFH cells (4.17 +/- 1.3 and 3.86 +/- 1.24). Statistical analysis showed that differences between GCTs and MFH were highly significant for both mononuclear and multinucleate cells, whereas differences between GCTs and NOF were significant only for mononuclear cells.