The purpose of this study is to determine whether microwave ablation is more effective in the treatment of simple renal cysts than conventional laparoscopic decortication.

Background: Simple renal cysts are the most common renal masses, and occur in half of all patients older than 50 years.They are usually asymptomatic and benign, asymptomatic and discovered incidentally. However, over time, these simple cysts can enlarge, become symptomatic and develop complications, requiring intervention.They can be managed by a variety of surgical and percutaneous methods, including percutaneous aspiration (with or without injection of a sclerosing agent), endoscopic marsupialization or excision, open surgery and laparoscopic cyst excision.Percutaneous aspiration and sclerotherapy have been described as safe and effective methods of managing symptomatic simple renal cysts without the cost and morbidity associated with conventional surgery and laparoscopy.However, laparoscopic decortications and simple aspiration is associated with a high recurrence rate because the cyst wall epithelium is responsible for active liquid production.

Purpose:To determine whether microwave ablation is more effective in the treatment of simple renal cysts than conventional laparoscopic decortication.

Method:

Inclusion Criteria:

• patients with sporadic, unilateral, newly diagnosed Bosniak Ⅰ, Ⅱ and ⅡF renal cyst
• patients agreeable to participate in this long-term follow-up study
• patients with normal contralateral renal function (differential renal function of >40% as determined by radionuclide scintigraphy)

Exclusion Criteria:

• patients' aged >80 years
• patients not able to tolerate the microwave ablation procedure
• patients with previous renal surgery or history of any inflammatory conditions of the operative kidney
• patients with the renal cyst involving urinary collecting system
• patients with other renal diseases,(including kidney stone, glomerular nephritis, etc.) which might affect the renal function of the operative kidney