Within each prostate zone, the glandular epithelium is generally simple columnar, but there may be patches that are simple cuboidal, squamous, or occasionally pseudostratified (Fig. 22.28). The alveoli of the prostatic glands, especially those in older men, often contain prostatic concretions (corpora amylacea) of varied shape and size, often up to 2 mm in diameter (see Fig. 22.28 and Plate 90, page 826). They appear in sections as concentric lamellated bodies  FOLDER 22.4 Clinical Correlation: Benign Prostatic Hypertrophy and Cancer of the Prostate chapter 22 Male Reproductive System PROSTATE G LAN D 811 Benign prostatic hypertrophy (nodular hyperplasia, BPH) occurs almost exclusively in the transitional and peri-urethral zones, leading to partial or total obstruction of the urethra (Fig. F22.4.1a). A widely accepted theory of the pathogenesis of BPH is related to the action of dihy-drotestosterone (DHT). DHT is synthesized in the stromal cells by conversion from circulating testosterone in the presence of 5-reductase. Once synthesized, DHT acts as an autocrine agent on the stromal cells and as a paracrine hormone on the glandular epithelial cells, causing them to proliferate (Fig. F22.4.1b). BHP is believed to occur to some extent in all men by age 80. Several options are available to treat BHP. Noninva-sive treatment includes medications (–receptor block-ers) to relax the prostate smooth muscles and relieve pressure on the compressed urethra. Clinical trials have shown that inhibitors of 5-reductase reduce the DHT concentration and thus decrease the size of the prostate and reduce urethral obstruction. Minimally invasive treatment options use laser, microwave, or radiofrequency energy to destroy the prostate tissue causing urethral obstruction. These include interstitial laser coagulation (ILC), microwave hyperthermia, and transurethral needle ablation (TUNA). Finally, a variety of surgical procedures are used to remove hypertrophied regions of the prostate gland. They include transurethral in-cision of the prostate (TUIP), a more extensive transurethral resection of the prostate (TURP), and most recently, a mod-ification of the TURP procedure that uses laser energy to vaporize the prostate tissue called Greenlight PVP. Cancer of the prostate is one of the most common cancers in the male: the lifetime risk of developing prostate cancer is 16.7% (1 in 6). The incidence of prostatic cancer increases with age, and it is estimated that 70% of men be-tween the ages of 70 and 80 will develop this disease. Tumors usually develop in the peripheral zone of the gland. In the past, early detection was uncommon, because the ab-normal growth of the tumor did not impinge on the urethra to produce symptoms that demanded prompt attention. There-fore, prostatic cancer was often inoperable by the time it was discovered. However, beginning in the late 1980s, the introduction of prostate-specific antigen (PSA) testing for aabba b FIGURE F22.4.1 • Benign prostatic hyperplasia (BPH) a. This photograph shows a horizontal section through the prostate gland from an individual with BPH. The cut section shows numerous well-defined nodules that compress prostatic urethra (marked with paper clip). b. Photomicrograph of prostatic glands shows the hypertrophy of epithelium lining the glands. Note that the cells form folds that protrude into the lumen of the glands. 200. (Reprinted with permission from Rubin E, Gorstein F, Schwarting R, Strayer DS. Rubin’s Pathology, 4th ed. Baltimore: Lippincott Williams & Wilkins, 2004; Fig. 17–40.) continued next page and are believed to be formed by precipitation of secretory material around cell fragments. They may become partially calcified.