Not always a problem. An isolsted kidney cyst is a fairly common finding, frequently noted on abdominal ultrasound. It is often benign, however, there are many types of cystic kidney disease that can be problematic. You should discuss this finding with your doctor to determine if further evaluation is indicated.
Kidney cyst. Over 95% of cysts on kidney are benign, common and not to worry. The other 5% require testing using ultrasound and either ct or MRI scans to see if they may be problematic and require removal. Many cysts in both kidneys is a congenital disease known as polycystic kidney disease and requires treatment by a nephrologist.
Recommend watching. Cysts on the kidney are common and usually benign. If ultrasound revealed it, then a repeat test in 6-12 months should be done for comparison, unless you have blood in the urine (on urine test in the lab), or there is a family history of kidney cancer or disease, in which case the test should be done more often. A ct scan can confirm and sometimes be more precise about the findings.