Kidney cysts are cavities inside the renal parenchyma which contain clear fluid.

Kidney cysts

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Simple cysts are benign and not associated with kidney cancer.

They differ from the inherited polycystic kidney disease in which the renal parenchyma is replaced by multiple cysts, a fact that can result in renal failure.

Its incidence increases with age; over 25% of patients after the age of 40 have a kidney cyst.

Causes of simple kidney cysts

The causes of simple kidney cysts are not clear.

An obstruction in the renal tubes may cause the formation of a simple cyst.

Symptoms of simple kidney cysts

Simple cysts are typically asymptomatic and do not affect kidney function.

Problems may arise when the cysts start to increase in size or are affected by a microbe.


Cysts are commonly an incidental finding during an imaging study conducted for another reason.

It is important to determine that it is a simple cyst and not kidney cancer.

For this reason, the following are used:

  • Renal ultrasound, which in most cases has the capacity to identify the damage
  • CT scan, which can accurately rule out the presence of cancer
  • MRI scan


Typically, simple kidney cysts do not require any treatment.

Only ultrasound monitoring is recommended.

Treatment is necessary in cases where the cyst is large-sized and causes problems.

The traditional treatment option is sclerotherapy; it is performed under local anesthesia and, with ultrasound guidance, the cyst is drained (paracentesis).

Next, after the cyst is drained, a special material is infused into the cyst to prevent recurrence.

When the cyst is very large, surgical treatment may be needed, either open or laparoscopic.