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What is Transitional cell carcinoma?
Transitional cell carcinoma: Cancer that begins in cells in the innermost tissue layer of the bladder. These cells are able to stretch when the bladder is full and shrink when it is emptied. Most bladder cancers begin in the transitional cells.
Cancer that is confined to the lining of the bladder is called superficial bladder cancer. Cancer that begins in the transitional cells may spread through the lining of the bladder and invade the muscle wall of the bladder or spread to nearby organs and lymph nodes; this is called invasive bladder cancer.
Transitional cell cancer can also grow in the lining of the kidney (called the renal pelvis), the ureters, and the urethra. In fact, patients with bladder cancer sometimes have a similar type of cancer in the lining of the kidneys, ureters, or urethra. Therefore, a complete evaluation of the urinary system is recommended for patients diagnosed with a cancer of the kidney, bladder, ureter, or urethra.
Subtypes of Transitional cell carcinoma
Not all Transitional cell carcinomas are the same. They are divided into several subtypes according to whether they are noninvasive or invasive and whether their shape is papillary or flat.
Invasive Transitional cell carcinoma
Noninvasive Transitional cell carcinoma: The cancer is only in the innermost layer of the bladder, the urothelium. It has not spread to deeper layers of the bladder.
Invasive Transitional cell carcinoma
Invasive Transitional cell carcinoma: The cancer has spread from the urothelium to the deeper layers of the bladder wall. In the past, some doctors used this term only when cancer had spread to the thickest and deepest muscle layer of the bladder (called the muscularis propria).
Currently, any bladder cancer not limited to the urothelium is classified as invasive. But it is very important to determine exactly how far into the bladder wall the cancer has invaded. Invasion of the thick, deep muscle layer of the bladder is much more serious than invasion that is limited to the superficial connective tissue layer (lamina propria) or the superficial, thin, muscle layer (muscularis mucosa).
Superficial Transitional cell carcinoma
Superficial Transitional cell carcinoma: This category includes bladder cancers that are noninvasive as well as some invasive cancers that have not spread deeply into the bladder wall. The cancer may only be in the layers of urothelial cells closest to the inside of the bladder, or it may have also spread to the thin layer of connective tissue (called the lamina propria) just beneath the urothelial cells. Once a cancer has invaded the bladder's main muscle layer, it is not considered superficial.
Papillary Transitional cell carcinoma
Papillary Transitional cell carcinoma: Papillary tumors have slender finger-like projections that grow into the hollow center of the bladder. They are sometimes said to resemble a branching type of cactus plant. Some papillary Transitional cell carcinoma grow only toward the center of the bladder. These are called noninvasive papillary Transitional cell carcinoma.
Papillomas are a benign type of papillary Transitional cell carcinoma. Since they are not cancerous, these tumors never spread to other parts of the body. They are successfully removed by surgery and rarely grow back. Patients with papillomas very rarely develop another papillary tumor elsewhere in their urinary system.
Papillary urothelial neoplasms of low malignant potential are cancers. These are usually successfully treated by surgical removal. But it is not unusual for patients with these tumors to develop one or more papillary tumors later on in other areas of their urinary system. Most of these other tumors resemble the original tumor, but occasionally the new tumor may be cancerous or even invasive.
Papillary Transitional cell carcinoma is a papillary tumor showing variable degrees of abnormality of the shape, size, and arrangement of cells. Those with relatively slight abnormality are called low grade. Although they rarely invade into the bladder wall, they often return after surgery. Carcinomas with greater abnormalities, called high-grade carcinomas, are more likely to invade into the bladder wall or even spread to other parts of the body.
Some papillary carcinomas grow inward toward the center and also grow outward into the bladder wall. These are called invasive papillary Transitional cell carcinomas.
Flat Transitional cell carcinoma
Flat Transitional cell carcinoma: Flat Transitional cell carcinomas do not grow toward the hollow part of the bladder at all. Some of these only involve the layer of cells closest to the inside or the hollow part of the bladder. These are called noninvasive flat Transitional cell carcinomas. Another name for noninvasive flat Transitional cell carcinomas is flat carcinoma in situ (CIS). Some flat Transitional cell carcinomas invade the deeper layers (away from the hollow part), particularly the muscle layer. These are called flat invasive Transitional cell carcinomas.
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