Benign neoplasm of the ureter is a rare condition where non-cancerous growths develop in the tubes that carry urine from the kidneys to the bladder. While these tumors are not cancer, they can still cause symptoms and require medical attention to prevent complications with urinary function.

Understanding Benign Tumors of the Ureter

A benign neoplasm is a type of tumor made up of normal, healthy cells that grow in an uncontrolled way but remain in one place. Unlike cancer, these tumors do not invade nearby tissues or spread to other parts of the body. When such a growth occurs in the ureter—the narrow tube connecting each kidney to the bladder—it is called a benign neoplasm of the ureter.^[3]

The ureters are thin tubes that form part of the urinary system. They are responsible for carrying urine produced by the kidneys down to the bladder, where it is stored until you need to urinate. Each person has two ureters, one for each kidney. These tubes are lined with cells called transitional cells or urothelial cells, which can stretch when urine passes through and then shrink back when empty.^[1]

Benign tumors of the ureter are uncommon. Unlike their malignant counterparts, benign tumors can grow quite large but they stay in the place where they started. This means they do not spread to other organs or tissues, though they may still cause problems by blocking the flow of urine or causing irritation to the urinary tract.^[2]

Types of Benign Ureter Tumors

There are several different types of benign growths that can occur in the ureter. The most frequently encountered is the fibroepithelial polyp. This type of benign tumor accounts for approximately two to six percent of all benign tumors found in the urinary tract.^[4]

Fibroepithelial polyps are growths that have a finger-like appearance. They are made of tissue that comes from the mesodermal layer—one of the early layers of cells that form during development in the womb. These polyps tend to occur most often in the upper part of the ureter, near where it connects to the kidney, or in the renal pelvis, the funnel-shaped area where urine collects before entering the ureter.^[4]

Other benign growths that can develop in the ureter include leiomyomas, which are made from smooth muscle cells; hemangiomas, which are made from blood vessels; and neurofibromas, which develop from nerve tissue. Less common types include lymphangiomas, granulomas, and endometriomas. However, fibroepithelial polyps remain the most common form of benign ureter tumor.^[4]

Epidemiology: Who Gets Benign Ureter Tumors?

Because benign tumors of the ureter are so rare, detailed statistics about how often they occur are not widely available. What is known is that these tumors can appear in people of any age, though certain patterns have been observed.^[4]

Fibroepithelial polyps, the most common benign tumor of the ureter, are typically found in adults between the ages of twenty and forty. However, they can also occur in children and have even been documented in newborn babies. Reports in medical literature differ on whether these tumors are more common in men or women. Some sources indicate they occur more frequently in women, while others have found them more often in young men. Most cases involve only one ureter rather than both.^[4]

In contrast, when discussing all tumors of the ureter—both benign and malignant—the condition is more commonly diagnosed in men and tends to appear after the age of fifty. Malignant tumors of the ureter are far more common than benign ones, and they occur primarily in older adults, with most cases diagnosed in people over sixty-five.^[2]

Causes and Origins

The exact reasons why benign tumors develop in the ureter are still not fully understood by medical researchers. Because these growths are so rare, it has been difficult to identify clear causes. However, several theories and possible contributing factors have been proposed.^[4]

Some experts believe that benign ureter tumors may have a congenital origin, meaning they result from abnormal development that occurs before birth. According to this theory, the cells in the ureter do not develop properly during fetal growth, which may later lead to the formation of a polyp or other benign growth.^[4]

Another possibility is that long-term irritation or inflammation in the ureter triggers abnormal cell growth. For example, the presence of kidney stones moving through the ureter could cause repeated injury and inflammation, which might contribute to tumor formation. Similarly, chronic urinary tract infections or other sources of ongoing irritation might play a role.^[4]

Other potential factors that have been suggested include allergic reactions, physical trauma to the urinary tract, exposure to harmful chemicals or carcinogens (substances that can cause abnormal cell growth), and hormonal imbalances. However, none of these factors have been definitively proven to cause benign ureter tumors, and more research is needed to understand the true origins of these growths.^[4]

Risk Factors

Because the causes of benign ureter tumors are not well understood, it is also difficult to identify specific risk factors that increase a person’s likelihood of developing these growths. However, certain conditions and circumstances may be associated with a higher risk.^[4]

People with a history of kidney stones may be at increased risk, as stones can cause repeated irritation and inflammation in the ureter. Chronic urinary tract infections or other conditions that lead to long-term inflammation in the urinary system might also contribute to the development of benign tumors.^[4]

Age appears to play a role, with most fibroepithelial polyps occurring in adults between twenty and forty years old, though they can occur at any age. There is no clear evidence that lifestyle factors such as smoking or diet significantly increase the risk of benign ureter tumors, though these factors are known to increase the risk of malignant tumors in the urinary tract.^[4]

Symptoms and Clinical Presentation

The symptoms caused by benign tumors in the ureter depend on the size and location of the growth, as well as whether it is blocking the flow of urine. In some cases, small tumors may not cause any symptoms at all and are only discovered incidentally during medical tests for other conditions.^[4]

The most common symptom of a benign ureter tumor is blood in the urine, known as hematuria. This occurs when the tumor irritates the lining of the ureter or blocks blood vessels, causing small amounts of blood to leak into the urine. The blood may be visible to the naked eye, giving the urine a pink, red, or brown color, or it may only be detectable under a microscope during a urine test.^[4]

Another frequent symptom is pain in the side of the body, particularly in the area between the ribs and hip known as the flank. This pain is often described as a dull ache or cramping sensation. It may come and go, especially if the tumor is partially blocking the ureter and causing intermittent obstruction of urine flow.^[4]

When a benign tumor grows large enough to significantly block the ureter, it can cause more serious problems. The blockage may lead to a backup of urine in the kidney, a condition called hydronephrosis. This causes the kidney to swell and can result in severe pain, similar to the intense cramping pain of kidney stones, known as renal colic. If left untreated, prolonged blockage can damage the kidney and impair its function.^[4]

In some cases, people with benign ureter tumors may experience acute urinary retention, meaning they suddenly become unable to pass urine. This is a medical emergency that requires immediate attention. Other possible symptoms include changes in urination patterns, such as needing to urinate more frequently or feeling an urgent need to urinate.^[4]

Prevention

Because the exact causes of benign ureter tumors are not known, there are no specific prevention strategies that have been proven to reduce the risk of developing these growths. However, maintaining overall urinary tract health may help reduce the risk of conditions that could contribute to tumor formation.^[4]

Drinking plenty of water throughout the day helps keep urine diluted and flowing regularly through the urinary system. This may help reduce the risk of kidney stones and urinary tract infections, both of which can cause inflammation in the ureter. Staying well-hydrated also helps flush out any bacteria or irritants that might contribute to chronic inflammation.

If you are prone to urinary tract infections, taking steps to prevent them may be beneficial. This includes urinating regularly and not holding urine for long periods, wiping from front to back after using the bathroom, and urinating after sexual activity. If you experience frequent infections, speak with a healthcare provider about possible underlying causes and prevention strategies.

Prompt treatment of kidney stones can help prevent repeated irritation and damage to the ureter. If you have a history of kidney stones, your doctor may recommend dietary changes or medications to reduce the risk of new stones forming.

Regular medical checkups and reporting any unusual symptoms, such as blood in the urine or persistent flank pain, can help ensure that any problems are detected and treated early, before complications develop.

Pathophysiology: How Benign Tumors Affect the Ureter

Understanding how benign tumors affect the normal function of the ureter helps explain why they cause symptoms and why treatment is often necessary. The ureter has a relatively simple but important job: to transport urine from the kidney to the bladder through rhythmic muscular contractions called peristalsis.^[1]

When a benign tumor develops in the ureter, it takes up space inside the tube or protrudes from the inner lining. Fibroepithelial polyps, in particular, often have a finger-like or stalk-like structure that extends into the hollow center of the ureter. As urine flows through the ureter, it must pass around or through the area where the polyp is located.^[4]

If the tumor is small, it may not significantly interfere with urine flow. However, as a benign tumor grows larger, it can partially or completely block the ureter. This obstruction prevents urine from flowing freely from the kidney to the bladder. When urine cannot drain properly, it begins to back up into the kidney, causing the kidney to swell. This condition, called hydronephrosis, increases pressure within the kidney and can cause pain and, over time, damage to the kidney tissue.^[4]

The physical presence of the tumor can also irritate the delicate lining of the ureter. This irritation may cause small blood vessels in the ureter wall to break, leading to bleeding. The blood then mixes with the urine, resulting in hematuria. The amount of bleeding can vary from microscopic amounts that are only visible under a microscope to larger amounts that visibly change the color of the urine.^[4]

In some cases, a polyp with a long stalk may act like a ball valve, moving back and forth in the ureter as urine pressure changes. This can cause intermittent obstruction, where the flow of urine is blocked at some times but not others. Patients with this type of obstruction often experience pain that comes and goes, rather than constant discomfort.^[4]

It is important to note that benign tumors do not invade through the wall of the ureter or spread to other organs. Unlike cancer cells, the cells that make up benign tumors remain well-organized and do not migrate to distant sites in the body. This is what makes them benign rather than malignant. However, their physical presence in the ureter is enough to cause significant problems with urinary function if they grow large enough or are located in a critical area.^[2]