Porth's Essentials of Pathophysiology, 4e

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Genitourinary and Reproductive Function

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largely unsuccessful. It also is thought that nonbacterial prostatitis may be an autoimmune disorder. Men with noninflammatory prostatitis have symp- toms resembling those of nonbacterial prostatitis but have negative urine culture results and no evidence of prostatic inflammation (i.e., normal leukocyte count). The cause of noninflammatory prostatitis is unknown, but because of the absence of inflammation, the search for the cause of symptoms has been directed toward extraprostatic sources. In some cases, there is an appar- ent functional obstruction of the bladder neck near the external urethral sphincter; during voiding, this results in higher-than-normal pressures in the prostatic urethra that cause intraprostatic urine reflux and chemical irri- tation of the prostate by urine. In other cases, there is an apparent myalgia (i.e., muscle pain) associated with prolonged tension of the pelvic floor muscles. Emotional stress also may play a role. Treatment methods for chronic prostatitis/pelvic pain syndrome are highly variable and require further study. Antibiotic therapy is used when an occult infection is suspected. Treatment often is directed toward symp- tom control. In men with irritative urination symptoms, α -adrenergic blocking agents and/or 5 α -reductase inhibi- tors (such as finasteride) may be beneficial. Noncentered treatment methods such as physical therapy, myofascial trigger point release therapy, and relaxation techniques may provide some symptom relief. 43 Benign Prostatic Hyperplasia Benign prostatic hyperplasia (BPH), also called nodular hyperplasia of the prostate, is a common age-related, nonmalignant enlargement of the prostate gland 14,15,44–46 (Fig. 39-11). It has been reported that more than 50% of men older than 60 years of age have BPH. 44 The dis- order is seen most frequently in Europe and the United States, and is seen least commonly in Asia. 15 The preva- lence of the disorder in the United States is higher among blacks than among whites. Pathogenesis. The pathogenesis of BPH is not com- pletely understood, but appears to involve an imbalance between cell proliferation and cell death that results in an overgrowth of the mucosal glands of the prostate. There is an increased number of epithelial cells and stro- mal components of the periurethral area of the prostate, but no clear evidence of increased epithelial cell prolif- eration. Instead, it has been proposed that the cause of the hyperplastic process is decreased cell death, result- ing in an accumulation of senescent cells. 14 The main androgen in the prostate is dihydrotestosterone (DHT), which is formed in the prostate from the conversion of testosterone by the enzyme 5 α -reductase. It is thought that DHT-induced growth factors increase the prolif- eration of prostatic stromal cells and decrease the death of the epithelial cells. The discovery that DHT is the active factor in BPH provides the rationale for the use of 5 α -reductase inhibitors in the treatment of the disorder. Benign prostatic hyperplasia is characterized by the for- mation of large, discrete lesions in the periurethral region

of the prostate rather than the peripheral zones, which commonly are affected by prostate cancer (Fig. 39-12). The anatomic location of the prostate at the bladder neck contributes to the obstructive properties of BPH and development of lower urinary tract symptoms. There are two distinct components of the obstruction: static and dynamic. 44,45 The static component of BPH is related to an increase in prostatic size and gives rise to symptoms such as a weak urinary stream, postvoid dribbling, frequency of urination, and nocturia. The dynamic component of BPH is related to prostatic smooth muscle tone, which is mediated by α 1 -adrenergic receptors. The recognition of the role of α 1 -adrenergic receptors on neuromuscular function in the prostate is the basis for use of α 1 -adrenergic receptor blockers in treating BPH. A third component, detrusor instability and impaired bladder contractility, may contribute to the symptoms of BPH independent of the outlet obstruction created by an enlarged prostate (see Chapter 27). It has been suggested that some of the symptoms of BPH might be related to a decompensating or aging bladder rather than being primarily related to outflow obstruction. An example is the involuntary con- traction that results in urgency and an attempt to void that occurs because of small bladder volume. 45 Clinical Course. The clinical significance of BPH resides in its tendency to compress the urethra and cause partial or complete obstruction of urinary outflow. As the obstruction increases, acute retention of urine may occur with overdistention of the bladder. The resid- ual urine in the bladder causes increased frequency of urination and a constant desire to empty the bladder, which becomes worse at night. With marked bladder FIGURE 39-11. Nodular hyperplasia of the prostate. Cut surface of a prostate enlarged by nodular hyperplasia shows numerous, well-circumscribed nodules of prostatic tissue.The prostatic urethra (paper clip) has been compressed to a narrow slit. (From Damjanov I, McCue PA.The lower urinary tract and male reproductive system. In: Rubin R, Strayer DS, eds. Rubin’s Pathology: Clinicopathologic Foundations of Medicine. 6th ed. Philadelphia, PA: Wolters Kluwer Health | Lippincott Williams & Wilkins; 2012:841.)