Vesicoureteral reflux is the most common and serious anomaly. As a major contributor to renal infection and scarring, it was discussed earlier in Chapter 20 in the consideration of
pyelonephritis. Abnormal connections between the bladder and the vagina, rectum, or uterus may create congenital fistulas.
Rarely, the urachus may remain patent in part or in whole (persistent urachus). When it is totally patent, a fistulous urinary tract is created that connects the bladder with the umbilicus. At
times, the umbilical end or the bladder end remains patent, while the central region is obliterated. A sequestered umbilical epithelial rest or bladder diverticulum is formed that may provide
a site for the development of infection. At other times, only the central region of the urachus persists, giving rise to urachal cysts, lined by either transitional or metaplastic epithelium.
Carcinomas, mostly glandular tumors resembling colonic adenocarcinomas, may arise in such cysts. These account for only a minority of all bladder cancers (0.1% to 0.3%) but 20% to
40% of bladder adenocarcinomas.
Figure 21-3Exstrophy of the bladder in a newborn boy. The tied umbilical cord is seen above the hyperemic mucosa of the everted bladder. Below is an incompletely formed penis with
marked epispadias. (Courtesy of Dr. John Gearhart, The Johns Hopkins Hospital, Baltimore, MD.)
Figure 21-4Cystitis with malacoplakia of bladder showing inflammatory exudate and broad, flat plaques.
Figure 21-5Malacoplakia, PAS stain. Note the large macrophages with granular PAS-positive cytoplasm and several dense, round Michaelis-Gutmann bodies surrounded by artifactual
cleared holes in the upper middle field.
TABLE 21-2-- Tumors of the Urinary Bladder
Urothelial (transitional cell) tumors
••Urothelial tumors of low malignant potential
••Papillary urothelial carcinoma
••Carcinoma in situ
Squamous cell carcinoma
Small cell carcinoma
described below may be seen at any site where there is urothelium, from the renal pelvis to the distal urethra.
There are two distinct precursor lesions to invasive urothelial carcinoma. The more common are noninvasive papillary tumors, which appear to arise from papillary urothelial hyperplasia.
 These lesions demonstrate a range of atypia, and several grading systems exist to reflect their biologic behavior. The other precursor lesion is flat urothelial carcinoma, which is simply
referred to as carcinoma in situ (CIS). This lesion is by definition high grade and hence not assigned a grade. In about half the patients with invasive bladder cancer, at the time of
presentation the tumor has already invaded the bladder wall, and there is no associated precursor lesion. In these cases, it is presumed that the precursor lesion has been destroyed by the
high-grade invasive component, which typically appears as a large mass that is often ulcerated. Although invasion into the lamina propria worsens the prognosis, the major decrease in
survival is associated with tumor invading the muscularis propria (detrusor muscle). Once muscularis propria invasion occurs, there is a 50% 5-year mortality rate.
Table 21-3 lists two of many systems of grading these tumors.    The World Health Organization (WHO) 1973 classification grades tumors into a rare totally benign papilloma
and three grades of transitional cell carcinoma (grades I, II, and III). A more recent classification, based on a consensus
TABLE 21-3-- Grading of Urothelial (Transitional Cell) Tumors
WHO/ISUP Grades *
Urothelial neoplasm of low malignant potential
Papillary urothelial carcinoma, low grade
Papillary urothelial carcinoma, high grade
WHO Grades †
Urothelial neoplasm of low malignant potential
Papillary urothelial carcinoma, Grade 1
Papillary urothelial carcinoma, Grade 2
Papillary urothelial carcinoma, Grade 3
WHO, World Health Organization; ISUP, International Society of Urological Pathology.
*Adopted as the WHO System in 2004.
†The 1973 WHO grades.
Figure 21-6Four morphologic patterns of bladder tumors.
Figure 21-7Cross-section of bladder with upper section showing a large papillary tumor. The lower section demonstrates multifocal smaller papillary neoplasms. (Courtesy of Dr. Fred
Gilkey, Sinai Hospital, Baltimore, MD.)
Figure 21-8Papilloma consisting of small papillary fronds lined by normal-appearing urothelium.
Figure 21-9Low-grade papillary urothelial carcinoma with an overall orderly appearance, a thicker lining than papilloma, and scattered hyperchromatic nuclei and mitotic figures (arrows).
Figure 21-10High-grade papillary urothelial carcinoma with marked cytologic atypia.
Figure 21-11 A, Normal urothelium with uniform nuclei and well-developed umbrella cell layer. B, Flat carcinoma in situ with numerous cells having enlarged and pleomorphic nuclei.
TABLE 21-4-- Pathologic T (Primary Tumor) Staging of Bladder Carcinoma
Date: 2016-04-22; view: 890