Human benign prostatic hyperplasia: a stromal disease? New perspectives by quantitative morphology.

Stereology is of great value for better understanding the pathomorphogenesis of benign prostatic hyperplasia (BPH) and the hormonally controlled mechanism of abnormal overgrowth of the prostate gland, especially the stromal component. In human BPH a fourfold absolute increase of the stromal part and a nearly double increase of the glandular part is indicated. The relative and absolute increase of the stromal part is surprisingly constant in spite of variation of human BPH. Stromal overgrowth can be viewed as a central feature of BPH implicating altered mesenchymal-epithelial relationship. At the ultrastructural level in man and dog the volume density of the secretory droplets and lysosomes of the glandular cells is reduced. Stereology data confirm furthermore the activation of the smooth muscle cells suggesting an induction of stromal growth possibly induced by estrogen and/or androgen and an important role in glandular-stromal interactions.