renal system

The Lower Urinary Tract: Ureters:

Congenital Anomalies: 1. Double ureters, The majority are unilateral and of no important clinical significance. 2. Ureteropelvic junction obstruction: usually presents in infants and children, more common in boys and on the left side. It is the most common cause of hydronephrosis in infants and children. 3. Dverticula: saccular in shape, are uncommon and usually found incidentally. 4. Hydroureter, may occur as congenital or acquired lesion.

Tumors And Tumor-Like Lesions of the Ureters

Primary tumors are rare. The most common are :  1. Fibroepithelial polyps,  2. Leiomyoma. 3. Transitional cell carcinoma, are sometimes multiple and occasionally occur concurrently with similar neoplasms in the bladder or renal pelvis.

Urinary Bladder: Congenital Anomalies

Diverticula:They may arise as congenital defects, or acquired. In both types, the diverticulum usually consists of a round to ovoid pouch that varies in diameter (1-10cm). Most of them are asymptomatic, but may predispose to infection and stone formation. Rarely carcinoma may arise in them.

Bladder Exstrophy: Implies developmental failure in the anterior wall of the abdomen and in the bladder, so that the bladder either communicates directly through a large defect with the surface of the body or lies as an open sac. There is tendency toward the development of tumor, mostly of adenocarcinoma.

Inflammation

Special Forms Of Cystitis: 1. Interstitial cystitis (Hunner Ulcer), this is a persistent painful form of chronic cystitis, occurring most frequently in women, and associated with inflammation and fibrosis of all layers of bladder wall. The condition is of unknown etiology, but is thought by some to be of an autoimmune origin. 2. Polypoidal cystitis, although indwelling catheters are the most commonly cause, any injurious agent may give rise to such lesion.

3. Malacoplakia: Refers to a peculiar pattern of vesical inflammation, characterized macroscopically by soft, yellow, slightly raised mucosal lesions and histologically by infiltration with foamy macrophages, mixed occasionally with multinucleated giant cells. The condition is related to chronic infections mostly by E. coli and Proteus species. It occurs with increased frequency in immunocompromised pt.

Urinary Bladder Neoplasms

About 95% of them are of epithelial origin, the remainder being mesenchymal. Most epithelial tumors are composed of transitional type

Transitional Cell Tumors

These represent about 90% of all bladder tumors and range from benign lesions to aggressive cancers. Many of these tumors are multifocal at presentation. Although most commonly seen in the bladder, they may be seen in the pelvis, ureters, and urethra.

Grading of the tumors

A most recent classification was adopted by the WHO in 2004,1. Urothelial papilloma.2. Urothelial neoplasm of low malignant potential.3. Papillary urothelial carcinoma, grade I.4. Papillary urothelial carcinoma, grade II.5. Papillary urothelial carcinoma, grade III.

Morphology

The gross patterns vary from purely papillary to nodular or flat. The tumors may also be invasive or non. Papillary lesions range in size between 1-5cm. They may be multicentric. Overall, the majority of papillary tumors are low grade and most arise from the lateral or posterior walls at the bladder base

TCC of the bladder

A transitional cell carcinoma of the urothelium is shown here at low power to reveal the frond-like papillary projections of the tumor

Transitional cell Papillomas

Represent 1% or fewer of all bladder tumors, Most commonly seen in younger patients. Usually solitary and exophytic, but, sometimes endophytic pattern is seen (inverted papilloma). The individual finger-like papillae have a central core of loose fibrovascular tissue covered by transitional epithelial cells that are Histologically identical to normal urothelium.

High Grade Papillary Urothelial Carcinomas

There is marked nuclear atypia, and some cells show frank anaplasia. Mitoses including atypical ones are frequent. These tumors have a much higher incidence of invasion into the muscular layer, a high risk of progression than the low grade lesions, and a significant metastatic potential. In most analyses, less than 10% of low grade cancers invade but as many as 80% of high grade cancers are invasive.


Aggressive tumors extend to adjacent organs and in 40%, there are regional lymph nodes metastasis. Hematogenous dissemination, principally to the liver, lungs and bone marrow, generally occur late.

Pathologic Staging Of Bladder Carcinoma

Noninvasive, papillary Ta Carcinoma in situ Tis Lamina propria invasion T1 Muscularis propria invasion T2 Microscopic extravesicle invasion T3a Grossly apparent extravesicle invasion T3b Invades adjacent structures T4

Other Types Of Carcinoma

Squamous Cell Carcinomas, represent about 3-7% of bladder cancers in general, but in endemic areas for urinary schistosomiasis, they occur much more frequently. Most are invasive, fungating tumors or infiltrative and ulcerative. Adenocarcinomas, are rare, some arise from urachal remnants or in association with extensive intestinal metaplasia.

Epidemiology and Pathogenesis

Carcinoma of the bladder is more common in men than women, in industrialized than in developing nations, and in urban than in rural dwellers. The M:F ratio for TCC is approximately 3:1. About 80% of patients are between 50 and 80 years. Some of the more important factors in causation bladder cancer include the followings 1. Cigarette smoking, is clearly the most important influence,  2. Industrial exposure to arylamines, particularly 2-naphthylamine. The cancer appears 15-40 years after the first exposure.

3. Schistosoma hematobium infection. The ova are deposited in the bladder wall and incite chronic inflammatory response that induces progressive squamous metaplasia and dysplasia and, in some instances, neoplasia. 4. Heavy long-term exposure to cyclophosphamide, which induces hemorrhagic cystitis and increases the risk of bladder cancer. 5. Long term use of analgesics. 6. Prior exposure of the bladder to radiation. The cancer occurs many years after the radiation.

Clinical course

Bladder tumors classically produce painless hematuria. Frequency, urgency and dysuria may be experienced as well. When ureteral orifice is involved, pyelonephritis or hydronephrosis may follow. The risk of recurrence and progression is related to several factors; tumor size, stage, grade, multifocality, prior recurrence rate, and associated dysplasia and/or carcinoma in situ in the surrounding mucosa.

Mesenchymal Tumors

Benign, collectively are rare, the most common is leiomyoma. Malignant, sarcomas are extremely rare. The most common in infancy and childhood is embryonal Rhabdomyosarcoma. In adults, Leiomyosarcoma is the predominant one.


Secondary Tumors :
Are most often as direct extension from adjacent organs. Lymphoma may also involve the bladder as part of systemic disease.