What is Inverted Urothelial Papilloma?
Inverted urothelial papilloma is an uncommon growth found in the kidneys, the tube that carries urine from the kidneys to the bladder (ureter), or in the bladder itself. It makes up less than 1% of all growths of the urinary tract. This condition was first described by a doctor named Paschkis in 1927, and since then, over 1,000 cases have been reported.
This growth is often found by accident while doctors are examining a patient for other conditions like a non-cancerous enlarged prostate, blood in the urine, or prostate cancer. This type of growth can sometimes cause visible or microscopic blood in the urine, but it usually doesn’t cause pain.
Neither the symptoms nor the appearance of inverted urothelial papilloma are unique to this condition, making it hard to identify based on those factors alone. The only way to definitively diagnose this condition is through a medical procedure that examines tissue under a microscope, known as a histopathological examination.
What Causes Inverted Urothelial Papilloma?
The exact cause of a bladder condition called inverted urothelial papilloma remains a mystery. However, many studies highlight chronic inflammation and irritation as important factors. Some researchers think that this type of bladder growth may occur in response to inflammation, long-lasting infections, smoking, blockages, or exposure to harmful substances that can cause cancer.
Meanwhile, other researchers argue that this growth results from an increase in cells from certain structures in the bladder called von Brunn’s nests. They believe this could be either a repair response or a response to inflammation.
Furthermore, some researchers have discovered certain signs in the growth, suggesting it could be linked to HPV infection. However, more specific tests looking for HPV DNA in the growth tissue haven’t been found. So, the role of HPV as a cause for inverted urothelial papilloma is still not proven.
Risk Factors and Frequency for Inverted Urothelial Papilloma
Inverted papillomas make up less than 1% of all bladder tumors. Generally, people in their 50s or 60s are most affected, but they can happen to anyone between the ages of 9 and 88. Males are affected more often than females, with the ratio being around 6 males for every female.
People who smoke can often have urothelial neoplasms, which means more bladder tumors. These tumors usually show changes in a gene called p53, and these cases often have more serious forms of the disease. However, inverted urothelial papillomas usually don’t have these gene changes, but they can have higher levels of p53.
- Inverted papillomas are less than 1% of all bladder tumors.
- People in their 50s and 60s are typically most affected, but it can happen between ages 9 and 88.
- Males are about 6 times more susceptible than females.
- Smokers often have urothelial neoplasms or bladder tumors.
- Tumors in smokers typically show p53 gene changes and usually involve serious disease forms.
- Inverted urothelial papillomas usually don’t have these p53 gene changes but can have higher p53 levels.
Signs and Symptoms of Inverted Urothelial Papilloma
Inverted urothelial papilloma of the bladder is a condition with symptoms that can be hard to pin down. Some people may not experience any symptoms at all while others may have a variety of issues. The most common is non-painful blood in the urine. Less common symptoms can include:
- Microscopic hematuria, which is blood in the urine that is only visible under a microscope
- Dysuria, or painful urination
- Flank pain, which is pain on the side of the body between the ribs and the hip
- Low back pain
- Occasional pyuria, or pus in the urine
- Vague abdominal discomfort
If the papilloma is located in the renal pelvis or ureter, then flank or low back pain may be the main symptoms presented. These could be accompanied by signs of urinary obstruction.
Testing for Inverted Urothelial Papilloma
Inverted urothelial papilloma, a type of noncancerous growth, is often found in the bladder. It is usually discovered by chance during medical investigations for other conditions like prostate enlargement, blood in the urine, or prostate cancer. Although ultrasound scans of the bladder can sometimes detect a growth, the best way to diagnose it is through a procedure known as cystoscopy.
In a cystoscopy, an instrument is used to look inside your bladder. If you have an inverted urothelial papilloma, your doctor may see a growth that looks like a smooth lump or like a cluster of small growths. The lump is usually smaller than 3 centimeters, but it can sometimes be larger, even up to 8 centimeters. Most people have only one, but it is possible to have multiple lumps.
Your doctor may also use magnetic resonance imaging (MRI) for further assessment. These growths often look similar on an MRI as they do during a cystoscopy. With an MRI, the doctor can see whether the growth is flat or lumpy and whether it has a stalk or not.
Urine tests are not typically helpful in diagnosing an inverted urothelial papilloma, as the growths are often covered by normal bladder cells. In some cases, further tests on the cells and genes might be needed to rule out bladder cancer.
A newer technique involving a substance called 5-aminolevulinic acid (5-ALA) is being used to help detect bladder growths. The substance can make the growths glow and is useful for helping to spot them. However, it doesn’t distinguish between cancerous and noncancerous growths. This could mean that inverted urothelial papillomas have a higher risk of turning into cancer than previously thought, but more research is needed to confirm this.
Treatment Options for Inverted Urothelial Papilloma
Inverted urothelial papillomas are a type of non-cancerous tumor found in the bladder. They typically don’t invade surrounding tissue. So, the common way to treat them is by completely removing them through a procedure called transurethral resection. This is a type of surgery where a device is passed through the urethra to remove these growths from the bladder.
It’s less common to find inverted urothelial papillomas in the upper parts of the urinary system. However, when they do occur, these growths tend to be large. To treat smaller growths in the upper urinary system, a doctor might perform a procedure called ureteroscopy. This involves using a thin, flexible tube with a camera on the end (ureteroscope) to view and remove the growths.
But for larger growths in the upper urinary system, different treatment options might be needed. These can include using a different method to reach and remove the growth (percutaneous access for direct resection), removing part of the ureter (the tube through which urine passes from the kidney to the bladder, known as partial ureterectomy), or even removing a kidney (nephrectomy).
What else can Inverted Urothelial Papilloma be?
When doctors diagnose inverted urothelial papilloma of the urinary bladder, a type of benign tumor, they need to make sure it’s not one of these other conditions that can have similar signs:
- Florid proliferation of Von Brunn nests (an unusual growth pattern of bladder cells)
- Brunn’s nest invaded by a more serious bladder cancer, urothelial carcinoma
- Exophytic papilloma (another type of benign bladder tumor)
- Urothelial carcinoma with an inverted growth pattern (a type of bladder cancer that grows inwards)
- A low-risk bladder cancer called “papillary urothelial neoplasm of low malignant potential”
- Cystitis glandularis (a benign bladder condition that can look like bladder cancer)
- Rarer conditions like nephrogenic adenoma, paraganglioma, carcinoid tumor or cystitis cystica
In inverted urothelial papilloma and urothelial cancer, there can be similarities in the physical appearance and microscopic features of the abnormal cells. However, urothelial cancer often shows cell clusters with irregular borders, increased cell growth around the clusters, and might show signs of spreading to lymphatic or blood vessels. The cells in urothelial cancer might also look different, show signs of cell death, and increased cell division.
Immunohistochemistry is a helpful technique to differentiate between urothelial cancer and inverted urothelial papilloma. This method involves staining the cells to observe specific markers. Signs like lower Ki-67 positivity (which indicates less cell multiplication) and being negative for CK20, unlike urothelial cancers, suggest the diagnosis of an inverted urothelial papilloma.
What to expect with Inverted Urothelial Papilloma
Inverted urothelial papilloma, a type of growth in your bladder, is generally considered to have a low risk of coming back (less than 5%), and is typically regarded as a benign, or non-cancerous, growth.
It’s important to note that if the tumor isn’t completely removed, it increases the risk of it returning. Some recent medical reports have questioned how harmless inverted urothelial papilloma actually is, suggesting it might have significant implications for long-term health checks known as cystoscopic surveillance – these are detailed examinations of the inside of the bladder using a special instrument.
Possible Complications When Diagnosed with Inverted Urothelial Papilloma
According to some recent research, a condition known as inverted urothelial papilloma of the urinary bladder could increase the risk of developing transitional cell carcinoma, a type of urinary tract cancer. Therefore, when a diagnosis of inverted urothelial papilloma is given, it’s critical to also rule out urothelial cancer and design a thorough follow-up plan. Studies have shown that sometimes between 2.5 and 10 percent of individuals with inverted urothelial papillomas of the bladder eventually develop urothelial carcinoma, generally over a period of 9 to 96 months.
Research Highlights:
- Inverted urothelial papilloma possibly increases the risk of transitional cell carcinoma.
- Upon diagnosis of this condition, to rule out urothelial cancer is essential.
- 2.5 to 10% of patients with this condition may develop urothelial carcinoma within a period of 9 to 96 months.
