Very common, but fortunately most often benign, almost one in two people are affected by kidney cysts. What exactly is a kidney cyst? What are the symptoms ? Can they be cancerous? How to treat them? The answers of Doctor Ala Chebbi, urological surgeon at the Mantaise region clinic.
What is a kidney cyst?
“A kidney cyst is a fluid-filled pocket that forms in or on the kidney” explains Dr Chebbi. Most of the time benign, they can vary greatly in size, ranging from small formations of a few millimeters to much larger cysts of several centimeters.
Lower back pain, blood in the urine: What can be the symptoms?
In the vast majority of cases, kidney cysts are asymptomatic, meaning they do not cause any symptoms or pain. “However, it happens that certain very large kidney cysts cause a feeling of discomfort or even pain in the lumbar region, but this is uncommon.” adds the surgeon. In certain rare cases, a large diameter renal cyst can be the cause of hematuria (blood in the urine).
Bosniak classification: How do you know if a cyst is benign or malignant?
The vast majority of kidney cysts are a simple pocket of water, and are therefore completely benign and have no consequences on health.
“However, in certain cases, the cyst is partly fluid and partly tissue, we then speak of an atypical cyst or cystic tumor of the kidney, which are then potentially malignant.” specifies Dr Chebbi. To identify the precise nature of this type of cyst and assess the risks, the patient is prescribed an imaging test, such as a CT scan or renal MRI. This examination will make it possible to classify the cyst on a scale from 1 to 4 according to different morphological characteristics: partitions inside the cyst, calcifications, tissue thickening…”This is the Bosniak classification, which allows kidney cysts to be described according to their malignancy potential.” summarizes the specialist. According to this classification, class 1 and 2 cysts are mainly benign. A class 3 cyst has a risk of approximately 50% of malignancy and the class 4 cyst is clearly malignant with solid components: the The risk of cancer is high and surgical treatment is generally indicated.
We then speak of cystic form of kidney cancer or cystic forms of kidney cancer.
Cancer: Can a kidney cyst progress and become cancerous?
“A fluid-filled renal cyst has an extremely low or even negligible probability of developing into a cancerous cyst: no monitoring is offered to the patient” indicates the urological surgeon. To summarize, the vast majority of kidney cysts are fluid and therefore benign and do not require monitoring. A small proportion of kidney cysts are immediately atypical with a risk of malignancy. But a fluid cyst does not does not develop into a malignant cyst.
Cause: What causes kidney cysts?
There are few identified causes of the appearance of kidney cysts. “Fluid-filled kidney cysts are more common in older people, but they can still appear at any age” underlines Dr Chebbi.
Certain genetic diseases are also the cause of kidney cysts, particularly autosomal dominant polycystic kidney disease. This genetic disease characterized by the formation of multiple cysts in the kidneys, leads to an increase in their size and a progressive loss of their function, with renal failure as a result.
Can a kidney cyst disappear spontaneously?
Fluid-filled kidney cysts never go away spontaneously, but that's not a worry because they don't cause significant symptoms or health problems.
Treatment: How to cure or remove a kidney cyst?
If the cyst is fluid, it is always benign and without risk of progression: no treatment or monitoring is offered.
In the case of a potentially malignant cystic tumor, biopsy can be discussed depending on its feasibility. If biopsy is impossible, partial nephrectomy is proposed as first intention, in order to remove the cystic lesion while sparing the kidney. “The feasibility of this partial nephrectomy procedure is estimated based on the size of the cystic lesion, its location and its depth in the kidney. If partial nephrectomy is impossible, it will sometimes be necessary to do a total nephrectomy..