Urogenital ImagingUrothelial tumour
(also called transitional cell papilloma),
tumour that may occur anywhere in the bladder
mucosa, being either papillary (papillomas, transitional cell
carcinoma in situ, and papillary
carcinoma) or nonpapillary (
invasive transitional cell
carcinoma, squamous cell
carcinoma, adenocarcinoma and spindle giant cell
carcinoma) (see also
carcinoma bladder). Most papillary tumours occur later in life (the sixth and seventh decade), and the clinical history is characterized by long survival with recurrent tumours. Papillomas are well differentiated epithelial tumours with less than six layers of cytologically normal transitional cells. This
tumour is rare and
benign, but tends to be multifocal and often recurs after surgery. Transitional cell
carcinoma in situ refers to full-thickness dysplastic changes in the bladder urothelium. Papillary urothelial carcinomas are graded (from grade I to
IV) depending on their histological and cytological differentiation. Grading is helpful in management, treatment and prognosis.
The important distinction is between well-differentiated tumours (classified as grade I or II and poorly-differentiated tumours (classified as grade III or IV). Of the nonpapillary tumours, invasive transitional cell carcinoma is a sessile tumour typically of a higher grade and more invasive than the exophytic neoplasms. Invasive urothelial carcinomas are highly malignant, and in most cases patients have a history of a prior papillary tumour. Early invasion of the lymphatics and infiltration of the bladder wall are common and are associated with a poor prognosis. Squamous cell carcinoma of the bladder is relatively infrequent, except in patients with schistosomiasis (Schistosoma haematobium infection). Adenocarcinomas are rare tumours of the bladder, usually arising in the trigone, which also carry a poor prognosis. Adenocarcinomas may also represent secondary involvement, and identification of the primary site of origin is important. Spindle (giant) cell carcinoma, also called carcinosarcoma, of the bladder is a rare tumour characterized by spindle and giant cells. These tumours tend to grow quite large, invariably invade the bladder wall, and have a poor prognosis.
Imaging evaluation of the bladder tumours has been mostly guided towards staging of bladder neoplasm. Detection of bladder neoplasm by imaging can be limited. It requires the use of contrast media on intravenous urography, and voiding cystogram studies. However, depiction of bladder tumours on intravenous urography is limited, and a number of tumours can be missed. Ultrasound, CT or MRI studies are all similarly sensitive in the depiction of bladder neoplasms. However, none of them can differentiate between benign or malignant lesions. Either CT or MRI are advocated for the staging of bladder neoplasms. MRI is considered superior to CT if the bladder neoplasm is located at the base of the dome of the bladder. The finding includes presence of the soft-tissue mass. For further discussion of staging of bladder neoplasm, see carcinoma bladder.
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