Simple kidney cysts are abnormal pouches containing fluid. The simple cyst is the most common form. Although its cause is not fully understood, we do know that the simple cyst is not an inherited condition. Single or multiple cysts may develop on small tubes in the kidneys.
Most often, simple cysts do not cause symptoms or harm the kidney. In some cases, however, pain can occur when cysts enlarge and press on other organs. Sometimes cysts become infected or suddenly start to bleed. Less often the cysts impair kidney function. Simple cysts can also cause high blood pressure.
Kidney cysts are found by taking pictures (CT scan and ultrasonography) of the kidneys. When simple cysts are found and there are no complications, no treatment is needed. If cysts cause symptoms, surgery may be needed.
As people get older, fluid-filled sacs, called "cysts," can form in the kidneys. These cysts are usually small, oval or round thin-walled sacs with water in them.
Kidney cysts are almost always benign (not cancer). Usually, the cysts cause no problems. In fact, people can go through life without knowing that they have them.
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 such as ultrasound, CT or MRI exams (ways of "taking a picture" of your insides) that are done because of problems in other parts of the body. The cysts are called "incidental" because they are found while a doctor is looking for something else and because of their benign nature.
If I have a kidney cyst, what will my doctor want to do?
First, your doctor will ask if you're having any problems such as pain on your side between your ribs and your hip, pain in your belly, a fever, frequent urination or blood in your urine. If you're having any of these problems, your doctor will probably examine you and order lab tests.
If you're not having any of those problems and your kidney cyst is small, you probably don't need any treatment. Your doctor might want to check the cyst again with a CT scan in 6 to 12 months. If you start having problems, your doctor might want you to have a CT or MRI scan of your kidney to see if the cyst is growing. Remember that most people with kidney cysts never have problems and never need extra CT scans.
If your kidney cyst is large or if it contains calcifications (hard, stony pieces) or dense tissue, you might need to have CT scans every so often so that your doctor can watch for changes in the cyst. To get more information about the cyst, your doctor might also want you to have an MRI scan.
Will I need surgery to remove a kidney cyst?
Probably not. Most kidney cysts are harmless and don't need to be removed. Your doctor will send you to a urologist (a doctor with special training in kidney problems) if your kidney cyst keeps getting bigger, if you have problems because of the cyst or if there is any concern that the cyst might be a cancer.
National Institute of Diabetes and Digestive and Kidney Diseases
31 Center Drive, MSC 2560
National Kidney Foundation
30 East 33rd Street
New York, NY 10016
American Kidney Fund
6110 Executive Blvd, Suite 110
Rockville, MD 20852
Evaluation of Incidental Renal and Adrenal Masses (American Family Physician 01/15/2001, http://www.aafp.org/afp/20010115/288.html)
I hope that helps, please let me know if you have more questions.