[A new treatment of simple renal cyst: percutaneous instillation of minocycline hydrochloride into simple renal cyst].

Minocycline hydrochloride was percutaneously instilled into simple renal cysts to prevent recurrence of renal cysts after the puncture and aspiration of cystic fluid. Fifty-six simple renal cysts in 51 patients were punctured with an 18-gauge needle under ultrasonographic guidance, and the cystic fluid was aspirated under fluoroscopic control. A single 100 mg or 200 mg dose of minocycline hydrochloride dissolved in 5 ml of distilled water was instilled through the needle into the renal cyst. The patients were followed up by computed tomographic (CT) scan and ultrasonography 1, 3, 6 and 12 months after the treatment. Efficacy was evaluated after 3 months or longer. Of 20 renal cysts instilled with 100 mg of minocycline, efficacy was excellent in 10, good in 6 and poor in 4. Of 22 renal cysts instilled with 200 mg of minocycline, efficacy was excellent in 10, good in 9 and poor in 3. No significant difference was noted between the efficacy rate of 100 mg and 200 mg treatments. Complications attributable to treatment were observed in 15 patients: moderate pain in one, slight pain in 6, slight fever in 8 and slight hematuria in one. Neither severe adverse reactions nor infections were observed in any of the patients. These results suggest that the percutaneous instillation of minocycline into simple renal cysts is a new, simple, safe and effective treatment to prevent recurrence of the cyst and additionally to prevent infection following the puncture.