Stromal and acinar components of the transition zone in normal and hyperplastic human prostate.

OBJECTIVE To analyse the histological components of the transition zone in both normal human prostate and benign prostatic hyperplasia (BPH), and to determine the volumetric density (Vv) of the different elements (connective tissue, smooth muscle cells, acini and total stroma). MATERIALS AND METHODS Samples of BPH tissue from the transition zone were obtained from 16 patients with clinical symptoms of bladder outlet obstruction who underwent open prostatectomy. The control samples comprised 16 transition zone samples from prostates obtained during necropsy of adults aged < 30 years (killed in accidents). The Vv of these components was determined by stereological methods. RESULTS The mean (sd) Vv in the controls and BPH samples were, respectively: connective tissue 40.47 (5.16) and 46.71 (9.91)%; smooth muscle cells 24.86 (2.74) and 31.56 (5.49)%; acini 28.73 (6.25) and 17.78 (10.87)%; all differences were statistically significant. CONCLUSIONS These results confirm the hypothesis that in BPH there is an increase in the stromal component, both smooth muscle fibres and connective tissue.