Kidney cancer

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Non-cancerous conditions of the kidney

A simple kidney cyst is the most common non-cancerous, or benign, condition of the kidney. A non-cancerous condition is a change to kidney cells, but it is not cancer. Non-cancerous conditions do not spread (metastasize) to other parts of the body and are not usually life-threatening.

A simple cyst is a round or oval fluid-filled sac. One or more cysts can develop in a kidney. Simple kidney cysts are very common in people over the age of 50. They’re also often found in people who are on dialysis because they have chronic kidney failure.

Risk factors

There are no known risk factors for developing simple kidney cysts. People who have kidney failure are more likely to develop one or more kidney cysts.


Simple kidney cysts rarely cause any symptoms. A large or infected cyst can cause:

  • pain in the side
  • urinating often
  • blood in the urine
  • fever


If you have symptoms or your doctor suspects a kidney cyst, you will be sent for tests. Tests used to diagnose or rule out kidney cysts or kidney cancer include:

  • ultrasound
  • CT scan

Most simple kidney cysts are found when an imaging test is done to check for other medical problems. When seen on an imaging test, simple kidney cysts have smooth, well-defined and rounded edges. This helps doctors tell them from kidney tumours.

Find out more about these tests and procedures.


Treatment options for simple kidney cysts include:

  • active surveillance
  • surgery to remove part or all of the kidney (called nephrectomy)


The invasion by and multiplication of organisms that cause disease (such as viruses, bacteria, yeast or fungi) in the body. Symptoms depend on where the infection occurs in the body and may include fever, inflammation and other problems.

An infection that occurs because of a weakened immune system is referred to as an opportunistic infection.


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