What is a urothelial papilloma?
Urothelial papillomas are mostly benign growths of the mucous membranes of the multi-layered covering tissue of the urinary tract (urothelium) . They usually occur on the back wall of the urinary bladder or on the side wall of the urinary bladder. More rarely, they can also form on the bladder roof, in the renal pelvis and/or in the ureters. A urothelial papilloma can become a malignant tumour. Urothelial papilloma occurs more frequently than average between the ages of 60 and 70, and men are more often affected by the disease than women.
What causes a urothelial papilloma to form?
A urothelial papilloma can form due to various exogenous noxae. These include tar products, for example, but also phenacetinabusus, benzidine and the carcinogenic degradation product ß-napthalene, which is also called aniline . Furthermore, chronic inflammations such as diverticulitis, the occurrence of urinary stones in the urinary tract (urolithiasis) or the tropical disease schistosomiasis are suspected to play a role in the development of urothelial papilloma. .
How does a urothelial papilloma develop?
A urothelial papilloma forms from cover cells. These in turn consist of a stratum polygonale and a stratum basale. The latter is located at the basement membrane, which consists of lamina propria and a loose connective tissue. A urothelial papilloma is therefore a hyperplasia (tissue enlargement) originating from the urothelium. If there are several urothelial papillomas, doctors call it papillomatosis. Papillomas that have more than seven rows of cells or in which nuclear atypia (so-called cell nuclei with an unusual shape, structure or size) are found are classified as papillomatous urothelial carcinomas. These occur in only about two percent of all tumour types of the urinary tract. Similar to a urothelial papilloma , a urothelial carcinoma also manifests itself through painless haematuria, , i.e. the discolouration of the urine caused by the presence of erythrocytes.
The urothelial papilloma can grow either exophytically or endophytically. Exophytic growth means that the growth can grow beyond a surface and thus lead to tumour growth, for example. If, on the other hand, the urothelial papilloma grows endophytically, this means that it grows inwards . In general, the urothelial papilloma does not differ from the surrounding urothelium.
What forms is a urothelial papilloma divided into?
In general, all forms of urinary bladder tumours are divided into solid and papillary growth. In almost 95 percent of all cases, all tumours originate from the urothelium. The remaining 5 percent of urinary bladder tumours originate from squamous cell and adenocarcinomas. As with other types of cancer, the tumour is classified into a tumour stage according to the TNM classification. According to this, the inverted papilloma carries the designation "Ta" and describes non-invasive papillary tumours that only infiltrate the urothelium at this stage. Higher-grade stages, on the other hand, also penetrate the connective tissue layer in hollow organs (lamina propria), the muscularis and/or the fatty tissue.
What are the symptoms of urothelial papilloma?
In a urothelial papilloma, painless haematuria occurs. This is the presence of erythrocytes in the urine. The urine can turn red, bloody or even coloured. Doctors then refer to as macrohaematuria with oxidation of the blood in the bladder. If there is no visible discolouration of the urine , doctors call it microscopic haematuria.
If the growth is already narrowing the urethra, an increased amount of residual urine may remain in the bladder. This in turn can lead to an increased urge to urinate, but also to an increased susceptibility to infections. A narrowing of the urethra can also lead to the following symptoms:
- Pain when urinating,
- weakened urine stream or urine dribbling,
- Discomfort after sexual intercourse.
As the disease progresses, the person may lose weight unintentionally and complain of night sweats.
How is urothelial papilloma diagnosed?
In general, if haematuria is suspected, a urine test strip is used. If this confirms the haematuria, a urethroscopy is performed. In this , a tissue sample is taken through the urethra under local anaesthetic (biopsy). If the suspicion of a urothelial papilloma is confirmed after the biopsy, further imaging procedures such as an ultrasound examination (sonography), a computer tomography (CT) and/or magnetic resonance imaging (MRI) are used. These imaging methods can help determine the extent to which the uroethelial papilloma has already spread to the surrounding tissue and the lymph nodes .
How can urothelial papilloma be prevented?
The development of urothelial papilloma can be prevented by drinking plenty of fluids and vitamin A. Currently, there is no diagnostic test that can detect the disease with certainty through a urinalysis . The use of a commercially available urine test is therefore not advisable as a screening test. If there is a suspicion of urothelial papiulloma or if the patient has symptoms of urothelial papiulloma, these should be clarified by a specialist.
How is urothelial papilloma treated?
In most cases, the surgical removal of the urothelial papilloma is attempted. Alternatively, radiotherapy can be given. In some cases, it may also make sense to reduce the size of the growth by means of radiotherapy or chemotherapy before surgery (neoadjuvant therapy). For the surgical removal of urothelial papilloma, the urethra may have to be partially or completely removed. If the growth is large or extensive, the entire bladder may also have to be removed.
What is the aftercare for urothelial papilloma?
After the therapy, regular check-ups are essential. This is to detect possible relapses (recurrences) as early as possible . During the check-up, the patient's blood is examined, but also an ultrasound examination and, if necessary , a CT or MRI are carried out.
The prognosis for a urothelial papilloma depends on the localisation, but also the spread and/or penetration depth of the growth.