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Oganes E. Dilanyan
Urologist, MD, PhD

Kidney Cyst

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Kidney cyst is usually a benign growth which resembles a thin walled sack filled with fluid. But there are several dangers that it poses: the cyst can become cancerous, it can compress the kidney thus disturbing it’s nutritional supply and rupture is also a risk. 

Diagnosis: Renal Cyst

Specific features: Renal cyst is one of those conditions that are often called “silent killers”. And it is true. There is usually no pain that is specific to this particular condition. Occasionally slight lower back pain might be present (or not) but who doesn’t get back pain.  Sometimes blood pressure goes up but the patients tend to just medicate for that and keep going. 
The result: By the time the patient is diagnosed the affected kidney has lost function due to long term constriction and the patient suffers from secondary complications such as high blood pressure. The kidney cyst is usually huge by this time. What is worse, sometimes a benign kidney cyst and turn malignant and become cancerous.  
This is why we think that the patients diagnosed with kidney cysts accidentally during a routine ultrasound are quite lucky. At least they do not yet have any complications and do not need to undergo long and complicated attempts to restore kidney function. The golden rule applies here: the earlier the patient is seen the quicker and easier it is to treat the condition.

Renal Cyst Surgery


Does every fluid filled growth on the kidney need surgery? No, far from it.
The surgery is only required if:

  • The cyst on the kidney is larger than 4 cm in size;
  • The cyst is small but is compressing the renal pelvis;
  • The cyst has multiple walls (called septation);
  • Bleeding or inflammation of the cyst.

We offer the following surgery options for kidney cysts: 

Kidney cyst paracentesis sclerotherapy. The aim of this procedure is to remove the fluid from the cyst cavity and replace it with a special solution that will glue the walls together from the inside. This method is used in the presence of parasitic cysts.

Laparoscopic kidney cyst removal – laparoscopic surgery is always preferable to open surgery. There is no incision, no pain and the patient can go home on the second day following laparoscopic kidney cyst removal.

“I had constant pulling pain on the left-hand side…massage and physio had no effect. Went to see a doctor, had an ultrasound and they found a large cyst on the left kidney”; “Prior to planning a pregnancy I decided to undergo a full medical check-up. I had no symptoms but at the ultrasound they saw a liquid-filled 6cm growth on the kidney”; “Constant high blood pressure which was treated with medication for 2 years. Then an ultrasound revealed that the cyst was compressing a blood vessel and this caused the blood pressure to rise”; “I knew I had a cyst on my right kidney. When I went for a follow up ultrasound they informed me it had become malignant”.

These are all common complaints of the patients that have this diagnosis.  I would like all my patients to understand one simple thing: the cyst is classified as a “new growth on the kidney”. In just over half the cases this is benign, but every time when I see a patient with this diagnosis I ask myself two questions: is this cyst parasitic and could it be malignant? 

“You, yes, you. Why did you tell the patient that he has mitral valve regurgitation? He did not understand you and you didn’t not even understand yourself!”

A quote from a famous professor.

Renal cyst is a thin-walled growth filled with fluid. It resembles a water filled balloon. It is important to understand that its internal surface constantly produces more fluid and the growth increases in size slowly but surely. Getting quite large it starts compressing the kidney and impairing its function.

Why are renal cysts dangerous?

There is a very dangerous misconception that this condition does not require any action. Let’s see what a renal cyst can lead to. 

  • Pain. Yes, the cyst’s walls do not have any pain receptors. And very often there is no pain. But as soon as renal capsule is overstretched by the growth the pain appears. Constant heaviness and discomfort can be present due to constant compression of not only the kidney but also of the psoas muscle.  
  • High blood pressure.  The kidney is a fascinating organ. The person’s entire blood volume passes through it in 3 to 4 minutes. As soon as the blood supply to the kidney decreases it start producing a special substance called rennin which causes the “renal” blood pressure increase. Unfortunately, renal hypertension is not easily controlled by medication.  
  • Malignant growths – renal cyst cancer. This is the most serious renal cyst complication. A malignant tumour consists of cells dividing uncontrollably. Renal cyst’s lepidic tissue consists of so-called epithelial cells that are constantly dividing. At some point the dividing mechanism is interrupted and a tumour develops. In that case the patient has to be treated for kidney cancer.

Renal cyst dangers are traumatic rupture, cancer and arterial hypertension.

Renal cyst: causes and symptoms

  • Simple renal cyst. One needs to understand that the kidney consists of a system of tubes and for some reason one of those tubes gets blocked, sometimes due to an inflammation. Over several years liquid slowly gets produced, the cavity grows and reaching a considerable size starts compressing the kidney disrupting its function.
  • Parasitic renal cyst. There are some parasites that can infect a person by transfer from animals such as dogs. These are dog tapeworm and alveococcus. Dog tapeworm cysts can be seen in the liver, lungs and the kidneys. The treatment should be carried out by a qualified specialist because damaging the cyst can lead to the disease spreading.

Renal cyst diagnosis

Renal cyst diagnosis.
Basically, when a urologist sees any patient with this diagnosis they need to answer 3 questions: 

  1. What is the nature of the disease?  Is it a simple or a parasitic cyst, or is it a malignant cyst.
  2. Does the cyst require surgical intervention? If it is a small benign liquid filled growth which does not disrupt kidney function then it does not require surgery. In all the other cases surgery is required. 
  3. What sort of surgery is required? There are at least three options: puncture of the cyst, laparoscopic removal or open surgery.

These are the questions we are trying to answer when we refer the patient for various tests. 

Renal cysts: diagnostic methods

Biochemical analysis

Allows us to answer two questions: Is the cyst caused by the parasites and how damaged is the kidney function? A number of factors are used to determine this: creatinine, urea and the factors that help to 

Kidney ultrasound

This is the main investigation that allows not only to see the growth but also detect if there is any compression of the ureter, tissue component and would the puncture and the sclerotherapy of the cyst be possible. The procedure also allows us to distinguish simple growths from those that are parasitic or cancerous.   

CT scan

Multi spiral computed tomography with contrast allows us to precisely assess a number of parameters such as kidney function, which we look at with the help of the contrast agent. The CT scan also helps to rule out malignant tumours and is also necessary to determine which method of treatment to use. 

Treatment and surgeries

Unfortunately, there are no therapeutic or alternative treatment options that are proven to help treat renal cysts. There are no remedies that that “dissolve” cysts or even reduce their size. This is why it is important to know which surgical treatment methods exist today.

Renal cysts: methods of surgeries

Renal cyst puncture

One of the main methods of renal cyst treatment. If the puncture itself is technically possible which can be seen during an ultrasound, it is still the preferred method of treatment. It is performed under local anaesthetic with constant ultrasound control using expert ultrasound machinery by BK-med.   During the puncture the liquid is removed and the sides of the cyst are glued together. This procedure is called “renal cyst sclerotherapy”. Puncture and sclerotherapy are used to treat simple cysts and in some cases in treatment of parasitic dog tapeworm cysts.

Laparoscopic renal cyst removal surgery

We use this method when the cyst is out of reach for using the puncture method and when the cyst size exceeds 7-8 cm or malignancy is suspected. Laparoscopic surgery is done using 3 punctures no longer than 5 mm and is characterised by total absence of pain and inflammation. Despite the fact that this is surgery the patients can be discharged as early as two days after surgery. We also use laparoscopic surgery for removal of parasitic dog tapeworm renal and liver cysts. 

Open surgery for the removal of renal cyst

Open surgery is only used in very rare cases when neither puncture nor laparoscopic surgery can be used due to various factors and contraindications and we have to perform standard open surgery. Open surgery can also be used to treat traumatic rupture of renal cyst. Unfortunately, we sometimes have to perform open surgery when a renal or liver cyst caused by alveococcus is suspected. 

Information for foreign patients:

If you require treatment for this condition please contact us. We will arrange admission to hospital on the day of your arrival and will carry out all the necessary tests. The operation will be carried out a day or two after your arrival. You will be able to go home after a couple of days.