Natural history of human prostate gland: Morphometric and histopathological analysis of Japanese men

BACKGROUND: To clarify the pathology of the development of prostatic disorders such as inflammation, cancer, and hyperplasia, we compared histopathological findings of the prostate according to age group. METHODS: Whole-mount sections of prostates were used to assess the relationship between age and prostate weight (n=962), prostate histological composition in the transition zone (TZ) and in the peripheral zone (PZ) (n=68), prostate histopathological findings by zone (n=102), and comparison of latent tumor development by age group (n=1,815). RESULTS: A rapid increase in prostate weight from birth to the 20s was followed by a slow rise thereafter. Volume increases (P<0.01) were observed in all components of glandular epithelium, glandular lumen, and stroma in the TZ from the 40s to 70s inclusive. In the PZ, the epithelial and stromal volumes tended to decrease in an age-dependent manner (P<0.05). Calculi and lymphocyte infiltration were detected at a relatively early age, with a tendency towards an age-dependent increase. Glandular dilation and nodular hyperplasia were noted first in the 30s group, also with a tendency towards age-dependent increase. Latent tumors were first detected in the 30s group (5.6%), and slowly increased thereafter. CONCLUSIONS: There was an age-dependent trend towards prostate glandular dilation and prostate enlargement with inflammation. It was demonstrated that tumor and hyperplasia have a long natural history, usually starting in the fourth decade of life, accompanied by dynamic changes with age in glandular tissue composition as well as cell proliferation activity.