What Is Nephrogenic Adenoma?
Nephrogenic adenoma (NA) is a benign growth typically found in the urinary bladder. It is characterized by tubular and papillary structures lined by a single layer of mitotically inactive bland cells. The cause of NA is not well understood, but it has been associated with chronic inflammation or irritation in the bladder. It is thought that NA results from the displacement and implantation of renal tubular cells, as this entity has been shown to be kidney donor-derived in kidney transplant recipients. NA is more common in men and adults, and symptoms can include frequent urination, hematuria (blood in the urine), and lower abdominal pain.
Nephrogenic adenoma (also known as nephrogenic metaplasia) is a rare tumor that occurs in the urinary bladder and is more common in males than females, with a 2:1 ratio. It can affect people of all ages but is more common in adults, and about ten percent of cases occur in children. The origin of nephrogenic adenoma is uncertain, but it is thought to be a metaplastic lesion that may originate from embryonic mesonephroid tissue or be caused by urothelial injury, immunosuppressive therapy, or intravesical instillations of Bacillus Calmette-Guérin.
What Are the Symptoms of Nephrogenic Adenoma?
Nephrogenic adenoma of the urinary bladder (NAUB) tends to present with irritative bladder symptoms such as urinary frequency and urgency, while presentation with hematuria is rare. At cystoscopy, NAUB may have a velvety appearance of the vesical mucosa that may be mistaken for papillary urothelial carcinoma due to its appearance. Previously, it had been thought that NAUB has a benign biological behavior with no malignant transformation, even in the presence of significant cytologic atypia. Still, subsequently, malignant transformations have been reported. It is important for patients with NAUB to undergo regular follow-up and monitoring to detect any potential changes in the lesion.
Symptoms of nephrogenic adenoma can vary depending on the location and size of the tumor. In general, symptoms may include-
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Blood in the urine (hematuria).
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Urinary frequency and urgency.
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Difficulty starting or maintaining urination.
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Pain or discomfort during urination.
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A feeling of incomplete bladder emptying.
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A lump or mass that can be felt in the lower abdomen or pelvic area.
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In some cases, the tumor may obstruct the urinary tract, leading to kidney damage or kidney failure.
How to Diagnose Nephrogenic Adenoma?
A nephrogenic adenoma is a rare benign tumor that typically develops in the urinary tract, most commonly in the bladder. The diagnosis of nephrogenic adenoma typically begins with a thorough medical history and physical examination. Imaging tests such as computed tomography (CT) scans or magnetic resonance imaging (MRI) can be used to help identify a mass or tumor in the urinary tract, which may be indicative of nephrogenic adenoma. However, imaging tests alone cannot confirm the diagnosis. A biopsy is needed to confirm the diagnosis and rule out other similar conditions. The biopsy is typically taken during a cystoscopy procedure, where a small camera is inserted into the bladder to visualize the tumor and take a sample of tissue.
What Are the Risk Factors for Nephrogenic Adenoma?
The exact cause of nephrogenic adenoma is not well understood, but certain risk factors have been identified. These include-
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Prior Radiation Therapy to the Pelvic Area: Individuals who have received radiation therapy to the pelvic area, such as for prostate or cervical cancer, have an increased risk of developing nephrogenic adenoma.
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Long-Term Bladder Catheterization: Individuals with a long-term indwelling bladder catheter, which is a tube inserted into the bladder to drain urine, have an increased risk of developing nephrogenic adenoma.
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Exposure to Certain Chemicals: Certain chemicals, such as those used in the rubber, textile, and dye industries, have been associated with an increased risk of developing nephrogenic adenoma.
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Male gender: Nephrogenic adenoma occurs more frequently in males than in females.
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Age: Nephrogenic adenoma is more common among older individuals.
How to Treat Nephrogenic Adenoma?
The treatment for nephrogenic adenoma typically involves the removal of the tumor. The most common approach is to remove the tumor through a cystoscopy, to visualize the tumor and remove it with specialized instruments. It may be possible to remove it completely if the tumor is small-sized. If the tumor has metastasized into surrounding tissue, a partial cystectomy (removal of a portion of the bladder) may be necessary.
In some cases, follow-up cystoscopies may be recommended to ensure that the tumor does not recur. If the tumor is not able to be removed or if the patient is not a good candidate for surgery, the options are limited. Some of the options are:
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Bladder Instillation of Mitomycin-C - Mitomycin-C is a chemotherapy drug that can be instilled directly into the bladder to shrink or slow tumor growth. The procedure is performed under anesthesia, and the drug is instilled directly into the bladder through a catheter. The drug, for a short period of time, is left in the bladder before being drained out, and the procedure is typically repeated every three to four weeks. This treatment option is considered for patients who are unsuitable for surgical intervention or patients who have a tumor recurrence after surgery.
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Transurethral Resection (TUR) - Transurethral resection (TUR) is used to remove tumors or abnormal growths in the urinary tract, including nephrogenic adenoma. The surgery requires to be done under general anesthesia. A cystoscope, which is a thin, lighted tube with a camera, is inserted through the urethra and into the bladder to visualize the tumor. Specialized instruments are used to remove the tumor through the cystoscope. TUR is considered a treatment option for nephrogenic adenoma, especially if the tumor is small and localized. The procedure is relatively safe, and recovery is usually quick. However, there are some risks associated with TUR, such as bleeding, infection, and bladder damage. A nephrogenic adenoma is a benign tumor, and it does not have the potential to spread to other parts of the body or cause death.
Conclusion:
Nephrogenic adenoma (NA) is a tumor in the urinary tract, most commonly in the bladder. It is characterized by papillary and tubular structures lined by a single layer of mitotically inactive bland cells with pale or clear cytoplasm. The cause of NA is not well understood, but it has been associated with chronic inflammation or irritation, previous bladder surgery, diverticula, renal transplantation, and intravesical BCG treatment. NA is more common in men and adults. Symptoms of NA can include blood in the urine, frequent urination, and lower abdominal pain. The diagnosis is typically confirmed by combining cystoscopy, biopsy, and imaging studies.
