Nephron-sparing surgery is still controversial for patients with renal cell carcinoma and normal contralateral kidney: risks predictable by AgNOR counts in satellite lesions.

Purpose: To determine whether nephron-sparing surgery is appropriate for patients with renal cell carcinoma (RCC) and a normal contralateral kidney.

Materials and methods: We prepared whole-area histologic sections from 58 cases of RCC to examine the features of satellite tumor lesions (STLs), the proliferative potential of which was evaluated by counting argyrophilic nucleolar organizing regions (AgNORs).

Results: We found three types of microscopic lesions: STLs, adenomas, and dysplastic foci, the latter two of which appeared to be preneoplastic. Of the 58 cases, STLs were observed in 27 (47%) and either adenomas or dysplastic foci in 19 (33%). At least one of the three types of lesion was found in 37 cases (64%). No correlation was found between the incidence of STL and the size of the main tumor, but the incidence tended to be higher in lesions of higher grade or stage. The STLs were located >2 cm from the margin of the main tumor in 6 of the 27 cases (22%). The mean number of AgNORs per high-power field was 5.09 +/- 1.53 (SD) in the main tumors, 4.21 +/- 1.36 in the STLs, and 2.27 +/- 0.07 in the adenomas and dysplastic foci.

Conclusions: These findings suggest that nephron-sparing surgery risks leaving STLs, which have considerable proliferative potential. Thus, nephron-sparing surgery must still be considered adventurous treatment in elective cases but can be recommended for patients who require nephron preservation.