Renal Cysts

What are Renal Cysts?

Renal or Kidney Cysts are benign cysts with smooth walls which distinguish from renal parenchyma and contain a clear or usually yellowish fluid. Simple cysts differ from cysts in patients suffering from PKD (Polycystic Kidney Disease). PKD is a hereditary disorder, in which the renal parenchyma is replaced with multiple cysts. PKD may affect renal function and in some cases patients may even need to undergo hemodialysis. Simple kidney cysts never affect renal function. Their incidence rate increases with age. It is estimated that about 25% of men and women aged 40-50 y.o. develop a simple renal cyst at some point in their life, while this rate rises to 50% in the age group above 50.

What are the causes of Simple Renal Cysts?

The etiology of simple kidney cysts is not fully clear. It is believed that renal tubules collecting urine are somehow obstructed and this induces the onset of cyst formation. The role of genetic factors in the development of simple renal cysts has not yet been investigated.

What are the symptoms of Simple Renal Cysts?

Simple Renal Cysts usually have no symptoms at all and do not cause impairment to the kidney so as to affect renal function. Only in very rare cases is there the risk of cysts being contaminated by some microbe. In such a case, the patient has pain, fever and fatigue. There are studies correlating cysts with high blood pressure in some patients; however, there is not sufficient evidence to support this.

How are Simple Renal Cysts diagnosed?

The diagnosis is usually set accidentally, when imaging screening is done for another irrelevant reason. When a cyst is detected, it has to be differentiated whether it is a simple renal cyst or a more severe condition, e.g. renal cancer. 

Imaging techniques used are::

  • Renal UltraSound (U/S). It is a simple, safe and painless imaging test widely used. In the majority of cases, it can determine whether the lesion is a simple renal cyst. If there are signs for a more severe condition, the therapisth physician will suggest further screening. 
  • CTscan. It can investigate a suspicious renal cyst with high accuracy and exclude the presence of malignancy. 
  • MRI. It has the same indications as CTscan for the investigation of renal cysts. 

How are Simple Renal Cysts treated?

Usually, there is no need for any treatment; however, simple renal cysts require to be checked on a regular basis by means of ultrasonography (U/S). Only in rare conditions -when the cyst is very large and causes problems- is there need for some intervention. The most frequently used method is Schlerotherapy. Under topical anesthesia and ultrasound guidance, the physician punctures the cyst percutaneously with the use of a special needle. The cystic fluid is aspirated and then the cyst is injected with a special sclerosing fluid, which aims at altering the cyst walls so that there will not be any renal cyst recurrence. Only in rare cases -when the cyst is too large- is there need for surgical intervention.  This may be either open surgery or , more often today, laparoscopically.