Assessment of Proliferative Index and its Association with Ki-67 Antigen Molecule Expression in Nodular Hyperplasia of Prostate

The cytoplasmic expression of Ki-67, a nuclear protein that appears primarily during the proliferative phases of the cell cycle was studied in benign tumours of the prostate gland. Archival prostatic tissue from 39 patients with nodular hyperplasia and no prior or subsequent prostatic carcinoma that have been obtained through transurethral prostatectomy (TURP) procedure, were used in this study. The proliferative index was assessed by calculating the number of actively proliferating cells in the H&E sections in varied histologic patterns like hyperplastic epithelium, proliferating stroma, normal glands and normal stroma. The nuclear protein Ki- 67 was analyzed by immunohistochemistry for determining the cytoplasmic positivity of the tumour cells. The proliferative index in the hyperplastic tissues was higher, indicating an increased activity of cellular proliferation, compared with the normal tissues, which was highly significant (p<0.01). Out of 39 cases of prostatic tissue, 25 (64 %) showed positivity for Ki-67 expression. Pearson's correlation test was applied to and showed significant association (p<0.05) between the intensity of Ki-67 expression with proliferative index. Comparisons of proliferative indices between the normal cells and tumour cells showed significant correlation, strongly suggesting the higher cell proliferation in the benign lesions. Enhanced expression of Ki-67 by the tumour cells suggests a growth imbalance in favour of cell proliferation that might ultimately promote prostatic hyperplasia.