Porth's Essentials of Pathophysiology, 4e

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Disorders of the Bladder and Lower Urinary Tract

C h a p t e r 2 7

Cancer of the Bladder Cancer of the bladder is the sixth most common malig- nancy in the United States, accounting for 7% of can- cers in men and 3% of cancers in women. 57–60 For some as-yet unexplained reason, African Americans have only half the risk of white European Americans. Most cancer of the bladder occur in older persons and is rare in those under the age of 50 years. Approximately 90% to 95% of bladder cancers are derived from the transitional epithelial (urothelial) cells that line the bladder. 57–60 These tumors can range from benign papillomas and low-grade papillary urothelial carcinomas to invasive urothelial cell carcinomas and highly malignant tumors. Urothelial papillomas are rare benign tumors, of which there are two forms: exophytic papillomas and inverted papillomas. 59,60 Exophytic papillomas have fonts or finger-like papillae with a central core of loose fibrovascular tissue covered by epithelium. Although considered benign some exophytic papillomas may recur or progress to carcinoma, thus long-term follow- up is necessary after excision. Inverted papillomas are benign nodular lesions that are cured by excision. Papillary urothelial neoplasms of low malignant potential share many histologic features with papillo- mas; however, they have a thicker urothelium and dif- fuse nuclear enlargement (Fig. 27-5). They may recur after excision and only rarely recur as higher grade tumors associated with invasion and progression. 59,60 Low-grade papillary urothelial carcinomas have fonts

potassium chloride solution and sterile water directly into the bladder. Increased pain with instillation of the potassium solution is considered a positive test and indi- cates urothelium dysfunction. There are a wide array of treatment options for inter- stitial cystitis/painful bladder syndrome. 55,56 Pentosan polysulfate sodium is the only FDA–approved oral ther- apy for the treatment of interstitial cystitis. The drug, which is an antidepressant, is thought to facilitate repair of the urothelium. Hydroxyzine (Vistaril), which is thought to control mast cell degranulation, and amitrip- tyline or nortriptyline, which inhibit neural activation, may also be used. Other nonspecific oral medications, such as analgesics, anti-inflammatory agents, and the urinary anesthetic phenazopyridine (Pyridium), can be used. Anticholinergic drugs are frequently used to con- trol pain and frequency. ■■ Urinary tract infections (UTIs) include several distinct entities, including asymptomatic bacteriuria, symptomatic lower UTIs such as cystitis, and upper UTIs such as pyelonephritis. ■■ UTIs involve host–agent interactions in which the defenses of the host compete with those of the infectious agent. Host defenses include the washout phenomenon in which the flow of urine washes bacteria out of the urethra, the bacteriostatic properties of the urine, the protective mucin layer that lines the bladder, and the antimicrobial properties of the normal periurethral flora in women and prostate secretions in men. Pathogen virulence derives from its ability to gain access to and thrive in the environment of the urinary tract, to evade the destructive effects of the host’s immune system, and to develop resistance to antimicrobial agents. ■■ Most UTIs ascend from the urethra and bladder. A number of factors interact in determining the predisposition to development of ascending UTIs, including urinary tract obstruction, urine stasis and reflux, pregnancy-induced and aging changes in urinary tract function, and presence of urinary tract catheters. ■■ Interstitial cystitis or painful bladder syndrome is a chronic, often debilitating, condition that is characterized by urinary frequency, urgency, and severe suprapubic pain. Unlike bladder inflammation caused by a bacterial infection, the condition occurs in the absence of other pathology. SUMMARY CONCEPTS

Localization

Type

Dome 10%

Papillary 80%

Ureter

Papilloma

Posterior and lateral wall 70%

Papillary and invasive Flat invasive Flat noninvasive

Trigone and bladder neck 20%

Carcinoma in situ 3%

Urethra

FIGURE 27-5. Urothelial neoplasms. Most tumors are located on the posterior and lateral walls; trigone and bladder neck are involved less commonly. Malignant tumors may be papillary or flat. Both flat and papillary tumors may be invasive or noninvasive. Benign transitional cell papillomas are rare. (Adapted from Damjanov I, McCure 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; 2012:819.)