Rare cancerous bladder tumours
Rare cancerous, or malignant, bladder tumours make up less than 10% of all bladder cancers. The following cancerous tumours of the bladder are rare.
Squamous cell carcinoma
Squamous cell carcinoma of the bladder develops when urothelial cells, or transitional cells, in the lining of the bladder (called the urothelium) change into squamous cells. This change is often due to long-term inflammation, which is linked with constant bladder irritation from catheters (tubes) placed in the bladder for a long time, chronic bladder infections or bladder stones.
Squamous cell carcinoma makes up about 5% of all bladder cancers. It is more common in certain countries, such as Egypt, and is most often linked with schistosomiasis (an infection caused by a parasitic worm). Squamous cell carcinoma is usually treated with surgery, with or without chemotherapy and rarely with radiation therapy.
Adenocarcinoma of the bladder starts in gland cells in the lining of the bladder (called the urothelium). It develops when cells in the urothelium change due to chronic irritation caused by a blockage (obstruction), an infection or a non-functioning bladder. It makes up less than 2% of all bladder cancers.
Different types of adenocarcinoma include:
- signet ring
- enteric type
- clear cell (mesonephric)
Adenocarcinoma is usually treated with surgery. A partial, or segmental, cystectomy may be done to remove the tumour along with part of the bladder around it. A radical cystectomy may be done to remove the bladder, surrounding tissue and lymph nodes. Chemotherapy is also used to treat adenocarcinoma. In rare cases, radiation therapy may be used.
The urachus is the connection between the navel (belly button) and the bladder. It develops in a fetus and remains as a fine ligament in an adult. In some people a cyst can form along the urachus, or the urachus can remain partly open. Whether or not these abnormalities happen, the urachal remnant can turn cancerous. Urachal cancer usually develops where the urachus joins the top of the bladder. Urachal cancer is a type of adenocarcinoma of the bladder.
This cancer is usually treated with a radical cystectomy (surgery to remove the bladder, surrounding fatty tissue and nearby lymph nodes), although some people can have a partial cystectomy because the tumour is at the top of the bladder. Chemotherapy may be given after surgery.
Small cell carcinoma
This is an aggressive cancer that is thought to begin in neuroendocrine cells. Some people with urothelial carcinoma, or transitional cell carcinoma, may also have small cell carcinoma.
Treatment for small cell carcinoma always starts with chemotherapy. Chemotherapy is used because there is a very high risk that this cancer will spread, or metastasize. After chemotherapy the bladder is either removed (with a radical cystectomy) or treated with radiation therapy.
Lymphoma is rarely found in the bladder. It can be a primary bladder lymphoma, which means that it starts in the bladder. It can also be part of a lymphoma that is present in different parts of the body. Experts aren’t sure why lymphomas develop in the bladder.
Sarcoma in the urinary tract is uncommon. Tumours diagnosed as sarcoma are sometimes reclassified as sarcomatoid urothelial carcinomas (also called urothelial carcinosarcomas).
Different types of sarcoma include:
- leiomyosarcoma – the most common type
The only risk factor for sarcoma of the bladder seems to be radiation therapy given 20–30 years earlier. Sarcomas in the bladder are usually treated with surgery.
Occurring slowly, lasting a long time or progressing very gradually.