A 68-year-old man undergoes transurethral resection of the prostate (TURP) for benign prostatic hyperplasia. Histopathological examination reveals nodular hyperplasia of the prostate gland. Which of the following is the most common histological pattern seen in benign prostatic hyperplasia?

Explanation

## Benign Prostatic Hyperplasia: Histological Patterns **Key Point:** Mixed glandular and stromal hyperplasia is the most common histological pattern in benign prostatic hyperplasia (BPH), occurring in the majority of cases. ### Histological Patterns in BPH | Pattern | Frequency | Characteristics | |---------|-----------|------------------| | Mixed glandular and stromal | Most common (>60%) | Both epithelial and smooth muscle/fibrous tissue proliferation | | Stromal hyperplasia alone | 10–15% | Predominantly smooth muscle and fibrous tissue | | Glandular hyperplasia alone | 10–15% | Primarily epithelial proliferation | | Fibromuscular with atrophy | Rare | Atrophic glands with hyperplastic stroma | **High-Yield:** The transition zone of the prostate is the site of origin for BPH nodules. The hyperplasia involves both the epithelial (glandular) and mesenchymal (stromal) components, though the relative proportions vary. **Clinical Pearl:** The mixed pattern is clinically significant because: - Glandular component contributes to urinary obstruction via mass effect - Stromal component (smooth muscle) responds to alpha-blockers (e.g., tamsulosin) - This explains why combination therapy targeting both components may be more effective **Mnemonic:** **GSM** = Glandular, Stromal, Mixed (in order of complexity; Mixed is most common) ### Pathophysiology BPH arises from: 1. Increased DHT (dihydrotestosterone) sensitivity in stromal cells 2. Paracrine signaling between stroma and epithelium 3. Reduced apoptosis and increased proliferation 4. Estrogen-mediated stromal growth (in older men) The mixed pattern reflects the coordinated proliferation of both compartments under these hormonal and growth factor influences.