Non-urothelial bladder cancers

Definitions & Key takeaways

Non-urothelial bladder cancers are a small subset of bladder cancers that confusingly, often arise from the urothelium. They include cancers like squamous cell carcinomas completely made of squamous cells, and adenocarcinomas entirely consisting of glandular cells. They are believed to arise from chronic irritation of the bladder, especially from an infection by a flatworm called Schistosoma haematobium. People with non-urothelial bladder cancer may present with hematuria, dysuria, urinary urgency and frequency, and weight loss.

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Introduction0:00–0:14

There are two types of bladder cancers—urothelial and non-urothelial types. The urothelium is special type of transitional cell epithelium that forms a stretchy, protective barrier in the bladder.

Pathology0:14–0:44

The majority of primary bladder tumors are urothelial cell carcinomas also known as transitional cell carcinomas that obviously originate from the urothelium.
Somewhat confusingly, non-urothelial tumors, like squamous cell carcinomas and adenocarcinomas, also often arise from the urothelium layer but are distinguished by the way that their cells differentiate.

Squamous cell carcinoma of the bladder0:44–2:07

For example, the normal bladder surface is not normally lined with squamous epithelium, yet the cells in the urothelium can change shape and take on a flat, pancake-like appearance of squamous cells.
This non-cancerous change is called squamous cell metaplasia. If these cells begin to grow unchecked they can turn into a squamous cell carcinoma.
These tumors typically pop up in multiple locations, and show extensive keratinization, which is where the cytoplasm of the cells is filled with keratin, the same tough material in hair and nails.
Squamous cell carcinomas typically arise in response to chronic irritation like from recurrent urinary tract infections, and long-standing kidney stones.
Another cause, common in some parts of the world, is an infection with Schistosoma haematobium - a type of flatworm. In this infection, the infective larvae linger in the water and then burrow into human skin when given the opportunity, and travel to the liver to mature into adult flukes.
From there young flukes migrate to the urinary bladder veins to sexually reproduce and lay eggs in the bladder wall. These eggs can get urinated out, but they also cause chronic inflammation in the bladder wall which is how they lead to squamous cell carcinomas.

Adenocarcinoma of the bladder2:07–2:42

Primary adenocarcinomas of the bladder are more rare, but unlike squamous cell carcinomas, they frequently metastasize. These are usually solitary, and derive from glandular tissue, so they can often produce a lot of mucin.
Adenocarcinomas are the main form of bladder tumors in patients with bladder exstrophy, which is where the bladder protrudes through a birth defect in the abdominal wall and partially or completely sits outside of the body.
Adenocarcinomas can also develop in response to Schistosoma haematobium infections. Finally, it’s worth noting that adenocarcinomas of the urachus are quite similar to bladder adenocarcinomas.

Adenocarcinoma of the urachus2:42–3:02

The urachus is the fibrous tissue sitting at the dome of the bladder which serves as the remnant of the allantois, the canal that allows urine to flow from the fetal bladder into the amniotic sac.

Symptoms3:02–3:33

These non-urothelial bladder cancers typically present with bladder irritation and red blood cells in the urine, a condition called hematuria.
Since adenocarcinomas often secrete mucin, these cancers can also cause an excess amount of mucus in the urine called mucusuria.
While relatively rare, mucusuria as well as an abdominal mass is most commonly associated with urachal adenocarcinomas. To diagnose a cancer of the bladder it’s often helpful to use a cystoscope, which is a thin tube fitted with a light, and a camera that is inserted up the urethra and into the bladder—a procedure called cystoscopy.

Diagnosis3:33–3:56

Definitive diagnoses of squamous cell carcinomas and adenocarcinomas is based mainly on the cellular morphology of a resected tumor.

Treatment3:56–4:26

Small tumors can be resected with a cystoscope in a procedure called Transurethral Resection (TUR). But larger, invasive tumors could require a radical cystectomy - complete removal of the bladder along with dissection of the surrounding lymph nodes.
With urachal adenocarcinomas, the bladder dome, urachal ligament, and umbilicus are all generally removed. OK, as a quick recap.

Review4:26–5:02

Non-urothelial bladder cancers are a small subset of bladder cancers that confusingly, often arise from the urothelium. Squamous cell carcinomas are made completely of squamous cells while adenocarcinomas are composed completely of glandular cells.
These cancers often arise due to chronic irritation of the bladder, especially from Schistosoma haematobium infection. Thanks for watching, you can help support us by donating on patreon, or subscribing to our channel, or telling your friends about us on social media.