Page 716 - Textbook of Pathology, 6th Edition

700 urethritis (Chapter 4). The pathologic changes are similar to 3. Dietary factors. Certain carcinogenic metabolites of
inflammation of the lower urinary tract elsewhere but tryptophan are excreted in urine of patients with bladder
strictures are less common than following gonococcal cancer. These metabolites have been shown to induce bladder
infection of the urethra. cancer in experimental animals. The role of artificial
sweeteners like saccharin, coffee or caffeine and chronic
TUMOURS alcoholism in the etiology of bladder cancer in man is
controversial.
Majority of lower urinary tract tumours are epithelial. Both
benign and malignant tumours occur; the latter being more 4. Local lesions. A number of local lesions in the bladder
common. About 90% of malignant tumours of the lower predispose to the development of bladder cancer. These
urinary tract occur in the urinary bladder, 8% in the renal include ectopia vesicae (extrophied bladder), vesical
pelvis and remaining 2% are seen in the urethra or ureters. diverticulum, leukoplakia of the bladder mucosa and urinary
diversion in defunctionalised bladder. All these conditions
TUMOURS OF THE BLADDER are associated with squamous metaplasia and high incidence
of bladder cancer.
Epithelial (Urothelial) Bladder Tumours 5. Smoking. Tobacco smoking is associated with 2 to 3 fold

More than 90% of bladder tumours arise from transitional increased risk of developing bladder cancer, probably due
epithelial (urothelium) lining of the bladder in continuity to increased urinary excretion of carcinogenic substances.
with the epithelial lining of the renal pelvis, ureters, and the 6. Drugs. Immunosuppressive therapy with cyclo-
major part of the urethra. Though many workers consider phosphamide and patients having analgesic-abuse
all transitional cell tumours as transitional cell carcinoma, (phenacetin-) nephropathy have high risk of developing
others distinguish true transitional cell papilloma from grade bladder cancer.
I transitional cell carcinoma. Multicentric nature of urothelial cancer and high rate of
Bladder cancer comprises about 3% of all cancers. Most recurrence has led to the hypothesis that a field effect in the
of the cases appear beyond 5th decade of life with 3-times urothelium is responsible for this form of cancer. This is
higher preponderance in males than females. responsible for polychronotropism in bladder cancer i.e. the
ETIOPATHOGENESIS. Urothelial tumours in the urinary tumour tends to recur with time and develops at new
tract are typically multifocal and the pattern of disease locations within the urinary tract.
becomes apparent over a period of years. A number of Several cytogentic abnormalities have been seen in
SECTION III
environmental and host factors are associated with increased bladder cancer. These include mutations in p53, RB gene and
risk of bladder cancer. These are as under: p21 gene, all of which are associated with higher rate of
recurrences and metastasis.
1. Industrial occupations. Workers in industries that
produce aniline dyes, rubber, plastic, textiles, and cable have MORPHOLOGIC FEATURES. Grossly, urothelial
high incidence of bladder cancer. Bladder cancer may occur tumours may be single or multiple. About 90% of the
in workers in these factories after a prolonged exposure of tumours are papillary (non-invasive or invasive), whereas
about 20 years. The carcinogenic substances responsible for the remaining 10% are flat indurated (non-invasive or
bladder cancer in these cases are the metabolites of β- invasive) (Fig. 22.46). The papillary tumours have free
naphthylamine and benzene. floating fern-like arrangement with a broad or narrow
2. Schistosomiasis. There is increased risk of bladder cancer, pedicle. The non-papillary tumours are bulkier with
Systemic Pathology
particularly squamous cell carcinoma, in patients having ulcerated surface (Fig. 22.47). More common locations for
bilharzial infestation (Schistosoma haematobium) of the either of the two types are the trigone, the region of
bladder. Schistosomiasis is common in Egypt and accounts ureteral orifices and on the lateral walls.
for high incidence of bladder cancer in that country. It is Histologically, urothelial tumours are of 3 cell types—
thought to induce local irritant effect and initiate squamous transitional cell, squamous cell, and glandular
metaplasia followed by squamous cell carcinoma. (Table 22.21).

Figure 22.46 Gross patterns of epithelial bladder tumours.