What are kidney cysts?
As people get older, sacs filled with fluid can form in the kidneys. These sacs are called "cysts." They are usually small oval or round thin-walled sacs with watery fluid in them.

Kidney cysts are almost always benign (not cancer). Usually, the cysts don't cause any problems. In fact, people can go through life without even knowing that they have them.

Some people have kidney cysts caused by an inherited disease called polycystic kidney disease (PKD). This disease can cause symptoms such as high blood pressure, pain in the back and side, blood in the urine or frequent kidney infections. Not all people who have PKD will have these symptoms.

How common are kidney cysts?
Up to 50 percent of people older than 50 years of age have kidney cysts.

How are kidney cysts found?
Almost all kidney cysts are found on tests that create a picture of your internal organs. These tests include ultrasound, computerized tomography (CT) or magnetic resonance imaging (MRI) scans. Sometimes kidney cysts are found during one of these tests that is being performed for another reason.

Will I need surgery to remove a kidney cyst?
If a cyst on the kidney isn’t causing any problems and the scans show that there is no blood flow in it (termed “non-enhancing), it probably won't need to be removed. Your doctor might want to check the cyst again with a CT scan or ultrasound in 6 to 12 months especially if the cyst is large, has irregular solid lumps on the sides, or contains calcifications (hard, stony pieces).

If the cyst on your kidney is getting larger with large lumpy areas that have blood flow (enhancing on CT scan or MRI), you may need to consider surgical removal as these signs are more often associated with kidney cancers.