DIGITAL IMAGE-ANALYSIS OF PROLIFERATIVE INDEX - 2 DISTINCT POPULATIONS OF HIGH-GRADE PROSTATIC INTRAEPITHELIAL NEOPLASIA IN CLOSE PROXIMITYTO ADENOCARCINOMA OF THE PROSTATE

A considerable amount of data has been collected showing the associati on of high-trade prostatic intraepithelial neoplasia (HGPIN) with aden ocarcinoma of the prostate, and many studies have yielded results that suggest that HGPIN is a precursor of carcinoma. A few studies have in dicated that HGPIN may, in some cases, be a sequels of prostatic adeno carcinoma. We examined the proliferative indices of HGPIN, carcinoma, and benign prostatic epithelium by computer-aided counting of Ki-67-po sitive nuclei in 15 cases in which HGPIN and carcinoma were in close p roximity. There were 13 radical prostatectomy specimens with prostate cancer and two cystoprostatectomy specimens with both transitional cel l carcinoma and prostatic adenocarcinoma First, we showed the accuracy of the computer-aided counting method compared with direct counting t hrough the binoculars of the microscope. Then proliferative activity w as assessed for each case by picking the two areas of carcinoma, the t wo areas of HGPIN, and the one area of benign epithelium with the grea test density of carcinomatous, dysplastic, and benign Ri-67-positive n uclei, respectively. The total number of nuclei and the number of posi tive nuclei were counted. Basal cells were not counted The mean prolif erative index uas higher for cancer (caindex, average 0.054) than for HGPIN (pinindex, average 0.048) (P<.05). We found that the 15 cases fe ll into two distinct groups. The average ratio of pinindex to caindex (pinindex/caindex) was lower in group 1 (0.72) than in group 2 (1.54) (P=.17), and when the results were corrected for the nonzero y-interce pts of the regression lines of pinindex versus caindex, the ranges wer e widely separated, and the difference between the means was statistic ally significant (0.15 v 0.62; P<.0001). A greater subjective similari ty between the nuclear features in the HGPIN and those of the correspo nding carcinoma was noted for the cases in group 2. The average value of bngnindx was 0.014. The value of bngnindx did not correlate with ei ther caindex or pinindex. We conclude that there may be two types of l esions with the morphological appearance of HGPIN and that they may ha ve different relationships to carcinoma Computer-aided counting of dig itized microscopic images is both labor-saving and as accurate as enum eration directly through the binoculars of the microscope. HUM PATHOL 29:620-626. Copyright (C) 1998 by WP. Saunders Company.