Lower urinary tract symptoms in patients with small prostates: Smooth muscle proliferation and calcification might be causative factors.

Objectives: The current study is designed to evaluate and compare the histological changes in the surgical samples of prostate taken from patients undergoing transurethral resection of prostate (TURP) for benign prostate hyperplasia (BPH) with different sizes.

Methods: Prostate surgical tissue samples were obtained from BPH patients undergoing TURP after taking informed consent. Ultrasound measure of prostatic weight and prostate-specific antigen (PSA) levels were obtained from the patients along with other clinical and demographic details. Tissue samples were fixed, processed, sectioned and stained with hematoxylin and eosin and Masson's trichrome to look for histological features, specifically smooth muscle proliferation. Immunohistochemical expression of bone morphogenetic protein (BMP)-2 was recorded to assess the calcification potential.

Results: Fifty-nine surgical samples were obtained from the patients of age range 50-90 years and body mass index (BMI) 15.6-33.3 kg/m² . The range of ultrasound measures of prostate weight was 20-137 g with PSA ranged 1.03-93.3 ng/mL. Patients with small-sized prostate had significant severe smooth muscle proliferation (P < .001). Prostate size/weight had significant positive association with BMI (P < 0.001, r = 0.543) and negative association with BMP-2 (P < 0.001, r = -0.654). Samples with severe smooth muscle proliferation were with increased BMP-2 expression (P < .001) and higher levels of PSA levels (P = 0.004). BMP-2 expression revealed positive significant association with PSA (P < .001, r = 0.432).

Conclusion: From this study we conclude that BPH patients with small-sized glands and high PSA levels have increased smooth muscle proliferation and calcification potential causing the symptoms of lower urinary tract symptoms in these patients.