Progressive activity in latent prostate carcinoma defined by argyrophilic staining of the nucleolar organizer regions (AgNOR).

Argyrophilic staining of the nucleolar organizer regions (AgNOR) was studied in 30 cases of benign prostatic hyperplasias (BPH), 17 cases of latent prostate carcinomas, 50 cases of clinical carcinomas and seven cases of metastatic lesions from prostate carcinomas. The criteria for these comparisons were the number of positive-staining dots per nucleus, the area of the dots, and a relative score determined by multiplying the number of positive-staining dots in the nuclei by the areas of the dots. Overall, there were no significant differences in these three parameters between BPH and latent carcinomas. Among latent carcinomas, however, significantly higher AgNOR scores were observed for infiltrative lesions than for non-infiltrative lesions. AgNOR dot number, area and score increased as tumors became less differentiated, with no significant differences detected in metastatic versus non-metastatic carcinomas. These results suggest that some latent tumors are similar in biological behavior, such as cell proliferation, to clinical carcinoma.