Clinical experience of single-session percutaneous aspiration and OK-432 sclerotherapy for treatment of simple renal cysts: 1-year follow-up.

PURPOSE To evaluate the efficacy and safety of single-session OK-432 sclerotherapy for the treatment of renal cysts. MATERIALS AND METHODS From October 2005 to November 2006, 48 patients (61 simple renal cysts) were included in the study. Indications were determined as flank discomfort (n = 37) or patient reassurance due to increasing size (n = 11). The simple renal cysts were aspirated under ultrasonography (US), at which point OK-432 was injected into the cyst. Follow-up was performed with US or computed tomography scan every 3 months until 1 year. Complete regression of the renal cyst or more than 70% reduction in size with no symptoms indicated a successful treatment. RESULTS Among 61 renal cysts of 48 patients, the overall success rate was 98.4%. Complete regression occurred in 46 cysts (75.4%), and more than 90% reduction in size occurred in 6 cysts (9.8%). A size reduction of 80% to 90% and 70% to 80% occurred in five (8.2%) and three cysts (4.9%), respectively. A size reduction less than 70% occurred in only one cyst (1.6%). The success of cyst regression was correlated with cyst volume. Clinical symptoms resolved in 100% of patients with symptomatic cysts, and there was no enlargement of the aspirated cysts at the 1-year follow-up. After the procedure, there were only some minor complications, such as mild fever, flank pain, and leukocytosis, which subsided with the conservative treatment. CONCLUSIONS Percutaneous OK-432 sclerotherapy is simple, safe, and effective, and it can be an alternative first-line therapy for simple renal cysts.