[Spontaneous rupture of infected renal cyst: a case report].

A 68-year-old man who had been followed at 1-year intervals for a left giant renal cyst was referred to our hospital for left flank pain and fever elevation. Abdominal computed tomographic scan revealed a giant cystic lesion of the left kidney suspected to be communicating with the urinary tract. Percutaneous puncture of this lesion was performed and the fluid was drained. The fluid was yellowish and cloudy, and E. coli was detected by its culture. Injection of contrast medium showed communication between the cyst and the urinary tract. The patient underwent drainage for a ruptured renal cyst. Rupture of a renal cyst is uncommon, and this is the 16th case reported in Japan.