Spontaneous and traumatic rupture of renal cysts: diagnosis and outcome.

Twenty-five patients with spontaneous or traumatic rupture of known renal cysts were encountered over an 18-year period. Blunt abdominal trauma and iatrogenic trauma during retrograde endoscopy accounted for four traumatic ruptures. In 21 patients, spontaneous communication occurred between the cyst and the collecting system or the perinephric space. Hematuria was the most frequent manifestation (21 patients [84%]), followed by flank pain (17 patients [68%]). The diagnosis was made by means of infusion nephrotomography in 22 patients, computed tomography in two, and retrograde pyelography in one. Follow-up information was obtained in 21 patients. The communication of the cyst with the collecting system closed spontaneously in 11 patients and persisted in two. Six patients were operated on because of coexisting stones, persistent hematuria, infection, or the uncertain nature of the cyst, and two underwent cyst evaluation by percutaneous needle aspiration. Renal cyst rupture is an infrequent, usually self-limiting event that may sometimes pose diagnostic dilemmas.