Pathogenesis of benign prostatic hyperplasia.

The pathogenesis of benign prostatic hyperplasia (BPH) remains largely unresolved. Three major theories have evolved over the years, each emphasizing a possible causative mechanism. The first theory, the dihydrotestosterone hypothesis, is based on the failure of BPH to develop in men castrated prior to puberty. The second, the embryonic reawakening theory, assumes a reawakening of the embryonic induction potential of prostatic stroma. The third, or stem cell theory, postulates the development of BPH through an increase in the number of stem cells or through an abnormal increase in clonal expansion of amplifying or transit cells. These mechanisms may act in concert.