Conservative and radiological management of simple renal cysts: a comprehensive review.

What's known on the subject? and What does the study add? Simple renal cysts are a common entity, which may need observation and follow-up or treatment. The study, for the first time, systematically reviews the indications for follow-up or radiological treatment of simple renal cysts. To review the conservative and radiological management of simple renal cysts a systematic literature review was performed. Simple renal cysts are commonly found in the adult population. Increasing age is highly associated with its incidence. When they remain asymptomatic they require neither treatment nor follow-up. When the shape of the cyst is slightly irregular follow-up is mandatory to exclude malignant progression. Symptomatic cysts require intervention. Ultrasound or computed tomography guidance have been effectively used for cyst puncture. However, simple fluid aspiration is ineffective leading to cyst recurrence. Aspiration should be accompanied with the injection of a sclerosing agent to destroy renal cyst epithelium. Several issues such as the ultimate technique and agent remain to be clarified. High rates of cyst disappearance and long-lasting cyst volume reduction have been reported with the use of various sclerosants. Ethanol in high concentrations and multiple injections is more commonly used with new agents showing similar efficacy and better complication profile. Studies comparing radiological intervention to surgical excision are lacking. Simple renal cysts may not require treatment when asymptomatic. Radiological intervention with the use of sclerosants needs further evaluation and comparison with other treatment methods.