Clinical and radiological course of simple renal cysts in children.

Objective: To evaluate the clinical and, particularly, radiological course of simple renal cysts in children.
Materials and Methods: Children with simple renal cysts were retrospectively evaluated, especially for change in the cyst diameter during follow-up and complications. In addition, the rate of increase in cyst size per year was calculated, and those characteristics of the cyst were analyzed to predict aggressiveness.
Results: Simple renal cysts were detected in 45 (21 male) patients. Mean ages at diagnosis and follow-up period were 7.4 ± 4.9 and 2.9 ± 1.8 years, respectively. Forty-one of the 45 patients were followed up for longer than 1 year. Diameter of the cyst increased in 20 (49%), decreased in 4 (10%), unchanged in 13 (31%), and disappeared in 4 (10%) of patients. The average size increase and average rate of enlargement in simple cysts were 0.3 mm and 1.0% per year, respectively. Furthermore, in 19 (95%) patients, the cyst size increased in the first 2 years. Among baseline parameters, only initial cyst size was an independent predictor of annual growth rates (beta = 0.628; P <.001). The relationship between the initial cyst size and annual growth rates was determined as positive (r = 0.459, P = .003). Two patients with large cysts developed severe complication in the first 6 months. One of these underwent nephrectomy because of rapid increase in cyst diameter (170 mm), renal artery/vein compression, and massive hematuria. In the other patient with severe loin pain regarding simple cyst (73 mm), percutaneous aspiration was performed.
Conclusion: Simple renal cysts in childhood tend to slowly increase in size. However, regular radiological follow-up might be important, especially in children with large size of cyst at diagnosis, because of more rapid increase in cyst size.
(Copyright © 2014 Elsevier Inc. All rights reserved.)