Nucleolar organizer regions in bone tumors.

Silver-stained nucleolar proteins (AgNORs) were counted in a variety of bone tumors. In osteosarcomas, the number of AgNORs was also quantified before and after chemotherapy. Malignant bone tumor cells possessed more than five small AgNORs (5.85 +/- 1.39). Nuclei of benign bone tumor cells had less than three (2.61 +/- 0.51). A significant difference in the number of AgNORs between osteosarcomas before chemotherapy (6.10 +/- 1.22) and after chemotherapy (4.20 +/- 1.07) was observed. (p less than 0.001). The number of AgNORs in osteosarcoma patients with better prognoses was smaller than that of osteosarcoma patients showing poor prognoses, but without significant difference. The results of the present study indicate that the AgNOR count might help in determining malignancy, evaluating the effect of chemotherapy, and deciding the prognosis.