Transitional Cell

• Transitional cells, also known as urothelial cells, line the urinary tract and are unique for their ability to stretch and contract.
• Their primary function is to protect underlying tissues from urine and facilitate bladder expansion.
• Transitional cell carcinoma (TCC) is a common cancer originating from these cells, primarily affecting the bladder.
• Symptoms of TCC often include blood in the urine, frequent urination, and painful urination.
• Risk factors for developing transitional cell cancer include smoking, exposure to certain chemicals, and chronic bladder inflammation.

What are Transitional Cells? Definition and Function

Transitional cells are a specialized type of epithelial cell that line the urinary tract, from the renal pelvis down through the ureters, bladder, and part of the urethra. This lining is specifically known as the urothelium. A key aspect of transitional cell definition and function is their remarkable ability to change shape. They can flatten when the bladder is full, allowing for significant expansion, and then return to a cuboidal or columnar shape when the bladder is empty. This elasticity is vital for the storage and passage of urine without damage to the underlying tissues.

Beyond their flexibility, transitional cells also form a protective barrier. They prevent the reabsorption of waste products and toxins from urine back into the bloodstream, maintaining the body’s internal balance. This barrier function is critical for preventing infections and chemical irritation of the urinary tract. The unique structure of these cells, with tight junctions between them, contributes significantly to their impermeability.

• Renal pelvis
• Ureters
• Urinary bladder
• Proximal urethra

Transitional Cell Carcinoma: Symptoms and Causes

Transitional cell carcinoma (TCC), also known as urothelial carcinoma, is a type of cancer that originates in the transitional cells lining the urinary system. It is the most common type of bladder cancer, accounting for about 90% of all cases, and can also occur in the renal pelvis, ureters, and urethra. Early detection is crucial for effective treatment.

Recognizing transitional cell carcinoma symptoms is vital for timely diagnosis. The most common symptom is hematuria, or blood in the urine, which may be visible (gross hematuria) or only detectable under a microscope (microscopic hematuria). Other potential symptoms include frequent urination, painful urination (dysuria), urgency to urinate, back pain (if the cancer has spread or is blocking a ureter), and pelvic pain.

Several factors contribute to transitional cell cancer causes and increase the risk of developing TCC. Smoking is the most significant risk factor, responsible for approximately half of all bladder cancers. Chemicals in tobacco smoke are absorbed into the bloodstream, filtered by the kidneys, and concentrated in the urine, where they can damage transitional cells. Other risk factors include exposure to certain industrial chemicals (e.g., aromatic amines used in the dye, rubber, and leather industries), chronic bladder inflammation or irritation, age (with the risk increasing significantly after age 55), a personal or family history of bladder cancer, and certain medications, such as cyclophosphamide.

According to the American Cancer Society, bladder cancer is the sixth most common cancer in the United States, with an estimated 83,730 new cases diagnosed in 2024, predominantly affecting men. (Source: American Cancer Society, Cancer Facts & Figures 2024).