Hi Cortical cysts don t generally cause signs or symptoms when small, however, dull pain in the back and side, fever and upper abdominal pain are common as the cyst grows bigger.The case of your friend is pretty small and may not require any treatment at that size.I will suggest a kidney function test be done to make sure the cyst is not interfering with kidney functioning.However, regular abdominal Ultrasound will be needed to evaluate the size of the cyst.If it becomes big and symptomatic, treatment options will include: puncture and drainage,then filling it with alcohol OR surgery to remove the cyst.Mild pelvicalyceal prominence may be normal radiologic findings and should not be a cause for concern if the kidney function tests are ok.A blood creatinine level will be useful. Do not be too scared. Hope my answer will help you Best regards