Prevalence of benign, precancerous, and malignant lesions of the prostate in men aged twenty (20) years and above

Abstract

Introduction: The main diseases of the prostate are prostatitis, benign prostatic hypertrophy and prostate cancer. One in ten men will develop clinically significant prostate cancer in their lifetime. Men who are diagnosed in their 50s and 60s probably started to develop the disease in their 30s and 40s. Prostatic Intraepithelial Neoplasia has been associated with prostate cancer on epidemiologic, clinical, genetic, and molecular levels . Objective: To determine the prevalence of carcinoma of the prostate, high grade prostatic intraepithelial neoplasia (HGPIN), low grade prostatic intraepithelial neoplasia (LGPIN),benign prostatic hyperplasia, atypical adenomatous hyperplasia, squamous metaplasia and prostatitis in autopsy prostate specimens and compare the findings with those from other geographical areas. Design: Descriptive cross-sectional study conducted from November 2006 to October 2007. Setting: The KNH mausoleum, the City Mortuary, Nairobi and the histopathology laboratory, University of Nairobi.

Subjects: One hundred and three prostates removed at autopsy from men aged twenty years and above who were not known to have prostate pathology. All the subjects were black Africans. Methods: A total of 103 prostatic gland specimens were examined by standard histopathological methods. The glands were fixed in 10% formalin, weighed, sliced at 2-4mm intervals from the apex to the bladder base and then paraffin embedded.

The paraffin blocks were sectioned with a microtome to 5urn sections that were mounted on microscopic slides. The histological slides were stained with haematoxylin and eosin. They were then examined by the principal investigator and the diagnoses confirmed by the supervisor. Another pathologist counterchecked some of the slides. Outcome measures: Age, prostate weights, benign prostatic hypertrophy, atypical adenomatous hyperplasia, squamous metaplasia, prostatitis, corpora amylacea, low grade prostatic intraepithelial neoplasia, high grade prostatic intraepithelial neoplasia, prostatic carcinoma. Results: All the 103 prostate gland specimens were processed and the histological results analyzed using the SSPS software. The average weight of all the specimens was 27.8 grammes. Four of the specimens were more than 40 grammes. Microscopy showed that 31.1% were essentially normal, 29.1% had chronic prostatitis, 27.2% microscopic hyperplasia, 23.3% LGPIN, 15.5%HGPIN, 10.7% atypical adenomatous hyperplasia, 1% prostate carcinoma in a 48 year old, 7.8% squamous metaplasia. Corpora amylacea was seen in 25.2% of the specimens. The mean prostate weights increased with age. Microscopic benign prostatic hyperplasia increased from 15..8% in the fourth decade to 80% in the seventh decade. Low grade prostatic intraepithelial neoplasia was 24% in the third decade, increasing to 28.6% in the fifth decade. High grade prostatic intraepithelial neoplasia was 4% in the third decade, increasing to 40% in the seventh decade. Conclusion: Premalignant lesions of the prostate are common in black Africans. The prevalence of incidental carcinoma was very low in this study. Benign prostatic hyperplasia starts early and increases with age. Chronic prostatitis was common in all age groups and it did not follow a particular pattern. Corpora amylacea was seen in all age brackets.