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Kidney Cysts


A kidney cyst is a fluid-filled structure that looks like a sac. It is also called a simple kidney cyst, which differs from a genetic condition called polycystic kidney disease (PKD), which causes numerous cysts to form, damaging the kidneys. Simple kidney cysts are oval or round and vary in size, ranging from 1 to 10 cm. Fluid in the cysts ranges from a clear to a pale-yellow color. The exact reason why simple kidney cysts form is not known. They may be acquired when there is injury or damage to the kidneys, which causes fluid to accumulate in a small area, leading to cyst formation.

Simple kidney cysts are often seen in normal kidneys. They are the most common form of masses formed in the kidneys, accounting for about 65-70% of all cases, and can be solitary, or multiple and bilateral. 

The prevalence of single kidney cysts varies. They occur more frequently in patients over 50 years of age and are twice as likely in men than in women. A Japanese study of 14,314 subjects found at least one kidney cyst present 12% of patients. These cysts were found through ultrasounds. There was a sevenfold increase in the prevalence of kidney cysts in people at 40 years of age to people at 80 years of age (5% to 36%). Most cysts increased in size over time, with the mean growth rate being higher in patients aged under 50 years (at 3.9mm versus 1.8mm per year growth seen in older patients).


Kidney cysts may not cause any symptoms until a cyst ruptures, hemorrhages, or grows and begins to press on nearby structures, such as nerves. If you do have a kidney cyst, you may experience: 

  • Pain in the ribs, back or stomach
  • Increased rate of urination
  • Blood in urine (pink, brown or red urine)
  • Fever

Simple kidney cysts have a clearly identifiable image on an ultrasound and CT scan. Since most simple kidney cysts are asymptomatic, they are often an incidental finding on an ultrasound that is conducted for an unrelated reason. If the ultrasound criteria for a benign simple kidney cyst are met, no additional imaging is required.

If the ultrasound is inconclusive, your medical team may recommend a CT scan. If calcifications or septations are detected, or if multiple kidney cysts are clustered in a pattern, that could mask an underlying carcinoma. Based on the CT findings, the lesion is classified into several categories.


Most simple kidney cysts do not require treatment. Your medical team may recommend regular monitoring. Treatment for symptoms, signs and/or complications is rarely required.


The medical and nursing staff of the Department of Nephrology are highly specialized and trained for the diagnosis, and treatment of kidney cysts. Additionally, our state-of-the-art imaging equipment in the GMI department of Radiology assists your medical team in the diagnostic procedure. 

24-hour Emergency Helpline

(+357) 25 208 000

Emergencies are not yet accredited of the General Health Care System

(+357) 25 208 000

Emergencies are not yet accredited of the General Health Care System.


Dr. Aris Angouridis

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