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Tumours of the Lower
Urinary Tract |
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Tumours of the lower urinary tract are derived
from the transitional cells of the urothelium
Most tumours of the lower urinary tract arise from transitional-cell epithelium
and are mainly caused by environmental agents excreted in high concentration in
the urine. A field change takes place in the whole of the
urothelium, such that all areas, from renal pelvis to urethra, are at risk of
development of neoplasia. For this reason, multiple tumours are common.
Transitional-cell tumours are most common in men, but are also fairly common in
women.
The majority of tumours derived from the transitional-cell epithelium occur in
the bladder and have a papillary growth pattern (papillary transitional-cell
carcinomas). The epithelium covering the papillae can vary from histologically
bland (low grade) to cytologically abnormal (moderate grade). All papillary
transitional-cell tumours are regarded as carcinomas, regardless of how bland
the epithelium appears on histological examination. Transitional-cell carcinomas
exhibiting severe cytological abnormalities (high grade) tend not to have a
papillary pattern, growing as solid, ulcerating lesions instead. It is well
documented
that patients can start with a low-grade tumour which, over time, develops
progressive cytological atypia and turns into a high-grade tumour.
A papillary transitional-cell carcinoma is seen arising from the dome of the
bladder
(a) as a fronded cauliflower-like lesion. Histologically
(b), lesions are composed of papillae covered with transitional epithelium.
Squamous cell carcinoma & adenocarcinoma of the bladder are uncommon
Transitional-cell carcinomas in the renal pelvis, ureter and urethra are
histologicaly similar in nature to those seen in
the bladder. Importantly, following on from the concept of a field change seen
in transitional-cell neoplasia, a patient who has had a tumour in one site is at
risk of developing a second tumour in another site in the urothelium.
Papillary transitional cell carcinoma fills the renal pelvis with dilatation of
the renal calyces caused by urinary obstruction. |
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We give here simplified and accurate information about the disease
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