Urothelial (Transitional) Carcinoma.
may arise in the urinary bladder,
renal pelvis and is the most common urinary bladder carcinoma.
More than 90% of bladder cancers originate from the transi-
tional epithelium (
) in the urinary system. Urothelial
carcinoma is most prevalent in older men but may occur at any
age. Risk factors include
, exposure to
, long-term use of cyclophosphamide, and
infection by the parasite
is also a risk factor for the development
squamous cell carcinoma
of the urinary bladder. Symptoms
include painless gross hematuria, frequency, urgency, and dysu-
ria. Urothelial carcinomas typically display a papillary morphol-
ogy and are subdivided into low and high grade depending on
cytologic features and the amount of architectural disorder pres-
ent. Treatment includes transurethral resection, chemotherapy,
immunotherapy, and radical cystectomy. Tumors have a high
recurrence rate after local excision.
Urinary bladder, bladder wall.
has three layers (
), similar to those in the ureter, but its wall is
much thicker. Thick mucosa and muscularis layers make up the
wall of the urinary bladder. The
is composed of exten-
arrangement gives the bladder the distensibility needed to store
consists of three
inner longitudinal, middle circular, and outer longitudinal smooth
muscle. These three smooth muscle layers are arranged in two dif-
ferent orientations to help the urinary bladder contract to empty
ciently. The outer layer of the bladder is mainly covered
(connective tissue); its superior (free) surface is cov-
, which is a layer of connective tissue with a lining
Urothelium, bladder wall.
gure shows the
(transitional epithelium) in a
relaxed state. The urothelial lining of the urinary bladder is thicker
than that of the ureter. The
of the urothelium are cuboi-
dal or columnar in shape, the cells in the middle layer of the urothe-
lium are polygonal, and the surface cells are
bulge into the lumen when the bladder is empty (relaxed state).
When the bladder is full, the urothelium is stretched, the cells
become ﬂ attened, and the thickness of the urothelium is greatly
reduced (see ±ig. 3-17B).