Renal Cyst

What is Renal Cyst?

Renal cysts, commonly known as kidney cysts are sac filled with fluid and is round in shape. It can multiply itself and are benign lesions but can become infected and cause pain if they increase in size. Some cysts are complex and contain solid substance rather than fluid.

On the other hand, some cysts are too small to be seen through naked eyes and can be only visible through a microscope. Some grow as large as a tennis ball and their increase in size can compress other organs which can lead to pain.

Types of Renal Cysts

The kidney cyst is classified into two forms-

  • Simple renal cyst: Simple cysts do not damage the kidneys or affect their function.
  • Polycystic kidney disease: Polycystic kidney disease (PKD) is an inherited condition that causes many cysts to form on the kidney. These cysts can damage the kidneys as they grow.

Based on imaging tests the Bosniak classification system of renal cystic masses divides renal cyst into five categories:

  1. BOSNIAK 1- simple renal cyst: Benign and do not cause any harm.
  2. BOSNIAK 2- minimally complex: Complicated but can be ignored.
  3. BOSNIAK 2F- minimally complex: Due to the increase in the number of septa and are minimally thickened calcification but are needed to be followed.
  4. BOSNIAK 3- indeterminate: Numerous nodules with multiple walls which are hyperdense.
  5. BOSNIAK 4- clearly malignant: Solid masses which contain necrotic component and is a surgical lesion.

Causes of Renal Cyst

There is not a clear-cut vision for the development of renal cyst in the kidney, but doctors assume the following reasons:

  • Age
  • Blockage in tube
  • When pouch-like structure called diverticula filled with the fluid forms in the weaker areas of the kidney

Risk Factors

Kidney cyst may occur at any age, but its risk increases with increase in age. A person above 40 years has 25% chances of having this cyst and at the age of 50, the chances increase to over 50%. This cyst is more common in men than in women.


Simple renal cysts show no sign of symptoms, but complex renal cysts show the signs and symptoms-

  • Pain in back, side or abdomen
  • Frequent urination
  • Bleeding during urination
  • Fever
  • Abdominal swell
  • Dark Urine
  • High blood pressure
  • Impair kidney function (rare case)


In rare cases, kidney cysts can lead to any of the following complications:

  • Ruptured & burst cyst
  • Infected cyst
  • Obstruction during secretion of urine out of kidney
  • High blood pressure


Renal cyst’s presence can only be identified through imaging tests which include:

  • CT Scan
  • Ultrasound
  • MRI
  • Urinalysis
  • Kidney function test


Simple renal cysts do not require any surgery as they are harmless but regular checking of the cyst if it is inflaming or not is necessary. If the cyst increase in size then further treatment should be done:


In this procedure, the doctors give local anesthesia and make a thin needle penetrate through the skin and pour out all the fluid. The doctor sometimes fills the empty pouch with alcohol which hardens the adjacent tissue and prevents recurrence.  Within the cyst, the scar down space is known as sclerosis.


If the cyst re-occurs or is more abundant in size then surgically it should be removed. With the help of general anesthesia, the surgeon inserts a laparoscope which is a lighted viewing camera and use different tools to drain the fluid. Then the cyst wall is burned or removed, and medications may be given to recover from surgery.



Be the first to comment

Leave a Reply

Your email address will not be published.