Silver-stained nucleolar organizer proteins in chondrosarcoma.

Silver-stained nucleolar proteins (AgNORs) were counted in primary chondrosarcomas of three histologic grades and in metastatic chondrosarcomatous lesions in the lung. The AgNOR numbers of neoplastic cells in primary tumors increased stepwise from grade 1 (4.42 +/- 1.11) through grade 2 (4.94 +/- 1.31) to grade 3 (6.97 +/- 1.10). There was a significant difference in AgNOR numbers between grade 3 and both grades 1 and 2 (p less than 0.001). Furthermore, the mean number of AgNORs in metastatic lesions (9.75 +/- 0.83) was significantly higher than that in primary sites (p less than 0.001). The number of AgNORs therefore reflects the grade of the chondrosarcoma. The results in the present study indicate that silver colloid staining is a useful technique for determining the histologic grade and evaluating the proliferative activity of chondrosarcomas.