Clinical evaluation of parapelvic renal cysts: do these represent latent urological malignant disease?

PURPOSE The parapelvic renal cyst is a relatively common finding on routine urological examination, but only rarely needs treatment. We here examined all parapelvic renal cyst patients who consulted our Department between April 1998 and December 2004 with the focus on potential for malignant development. MATERIALS AND METHODS A total of 73 patients were diagnosed as having parapelvic renal cysts by ultrasonography, in combination with computed tomography, and/or drip infusion urography in our Department. The background to diagnosis was suspicion of hydronephrosis in 15, flank and/or back pain in 15, and macroscopic hematuria and/or occult blood urine in 12. RESULTS There were 3 patients with renal pelvic cancer, and one patient with ureteral cancer. Nephro-ureterectomy was performed for all of these 4 cases. There were 10 patients with renal stones, three of which were given extracorporeal shock wave lithotripsy and one pyelonephrolithotomy. A further three underwent parapelvic renal cyst puncture, performed to preserve renal function or obtain release from symptoms. The remaining 3 cases were symptomless, diagnosed after routine examinations, and were simply followed up, as with the other 59 cases with no stones or cancer. CONCLUSIONS Unless a parapelvic renal cyst causes pyelonephritis, symptomatic renal stones, or back discomfort, treatment is not indicated. However, the possibility that urological malignant disease may be encountered should be borne in mind and appropriate diagnostic measures should be performed. Furthermore, careful follow up of parapelvic renal cyst patients may be required.