The type of bladder cancer you have depends on the type of cell in which the cancer began. Pathologists can diagnose the type of cancer by looking at tumor cells under a microscope.

Urothelial Carcinoma of the Bladder

Most bladder cancers — about 90 percent — begin in the cells on the surface of the bladder’s inner lining. This type of cancer is called urothelial carcinoma (also called transitional cell carcinoma). Most urothelial carcinomas are a form of non-muscle invasive bladder cancer (NMIBC). That means the tumor stays within the bladder’s inner lining.

Urothelial carcinoma also has rarer subtypes, or “variants.” These differ depending on how the cells appear under a microscope. The variant of urothelial carcinoma affects the treatment. The variants are called:

• plasmacytoid
• nested
• micropapillary
• lipoid cell
• sarcomatoid
• microcystic
• lymphoepithelioma-like
• inverted papilloma-like
• clear cell

MSK has extensive experience in diagnosing and treating noninvasive bladder cancer and these rarer forms of urothelial bladder carcinoma.

Burt’s Story: A Urologic Oncologist Becomes a Bladder Cancer Patient

Learn how a bladder cancer specialist diagnosed with a very rare form of the disease turned to MSK for its expertise.

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Urothelial carcinoma is by far the most common form of bladder cancer in the United States. Other types of bladder cancer are rarer, although they may have a higher frequency in other parts of the world. These types include:

Squamous Cell Carcinoma of the Bladder

Squamous cell carcinoma is the second most common type of bladder cancer. It accounts for about 5 percent of bladder cancers in North America and Europe. This cancer begins in the thin, flat squamous cells that may form in the bladder after chronic inflammation and infection. Squamous cell carcinoma is most often found in parts of the world where a parasitic infection called schistosomiasis is widespread, such as the Middle East.

Adenocarcinoma of the Bladder

This rare form of bladder cancer accounts for about 1 percent of cases. Adenocarcinoma can be associated with certain bladder defects at birth, as well as with chronic infection and inflammation.

Small Cell Carcinoma of the Bladder

This aggressive form of the disease begins in small nerve-like cells in the bladder called neuroendocrine cells. Small cell carcinoma makes up about 1 percent of bladder cancers. It is often detected at an advanced stage, after it has spread to other parts of the body. It usually requires a combination of treatments, including chemotherapy, surgery, and radiation therapy.