MORPHOMETRIC QUANTITATION OF STROMA IN HUMAN BENIGN PROSTATIC HYPERPLASIA

Objectives. Human benign prostatic hyperplasia (BPH) consists of three major histologic components: stroma, epithelium, and luminal space. For the relief of bladder outlet obstruction caused by BPH, quantitation of the histologic composition of BPH may aid in selecting treatment. To investigate variation between patients in the stromal percentage of BPH, we performed quantitative morphometry on specimens from patients with clinically significant bladder outlet obstruction obtained by three procedures: open prostatectomy, transurethral resection of the prostate (TURP), and prostate needle biopsy (PNB) just prior to TURP. Methods. Ten specimens obtained by each surgical procedure were analyzed. Specimens were stained with antibody to muscle-specific actin to mark the stroma; quantitation of stroma was accomplished by computer image analysis. Results. The percentage of stroma in all BPH cases ranged from 49.9% to 76.7% (mean, 65.4%, SD = 7.4). No significant difference was observed when comparing samples obtained by the three procedures (p = 0.70). Smooth muscle stromal composition was also quantified in PNB specimens. For these samples, a significant inverse relationship was found between the percentage stroma in the biopsy and the percentage of stroma composed of smooth muscle (r2 = 0.49; p = 0.021). Conclusions. The data demonstrated that the largest component of BPH was stroma, which comprised approximately 50% to 75% of the total hyperplastic tissue. The mean and range of stromal percentage were similar whether investigating large tissue samples from open prostatectomies or small samples from needle biopsies. PNB data indicated that an increased percentage of stroma may be due to increased nonmuscular elements in the stroma.