title: Spontaneous combined rupture of a pelvicalyceal cyst into the collector system and retroperitoneal space during the acquisition of computed tomography scan images: a case report.
abstract: BACKGROUND
  Pelvicalyceal cysts are common findings in autopsies and can manifest with a variety of patterns. These cystic lesions are usually a benign entity with no clinical significance unless they enlarge enough to cause compression of the adjacent collecting system and consequently obstructive uropathy. Few cases of the spontaneous rupture of pelvicalyceal renal cysts have been published and to the best of our knowledge there is no report of a combined rupture to collector system and retroperitoneal space documented during a multiphase computed tomography.
  
  
  METHODS
  We report a case of a 'real-time' spontaneous rupture of a pelvicalyceal cyst into the collecting system with fistulization into the retroperitoneum.The patient was a 78-year-old Caucasian man with a previous history of renal stones and a large pelvicalyceal renal cyst who was admitted to our Emergency department with acute right flank pain.A multiphase computed tomography was performed and the pre-contrast images demonstrated a right pelvicalyceal renal cyst measuring 12.0 × 6.1cm in the lower pole causing moderate dilation of the upper right renal collection system. In addition, a partially obstructive stone on the left distal ureter with mild left hydronephrosis was noted.The nephrographic phase did not add any new information. The excretory phase (10-minute delay) demonstrated a spontaneous rupture of the cyst into the pelvicalyceal system with posterior fistulization into the retroperitoneal space.
  
  
  CONCLUSIONS
  In this case study we present time-related changes of a rare pelvicalyceal cyst complication, which to the best of our knowledge has fortunately not been previously documented. Analysis of the sequential images and comparison with an earlier scan allowed us to better understand the physiopathological process of the rupture, the clinical presentation and to elaborate hypotheses for its etiopathogenesis.
authors.affiliation: Department of Radiology, Sírio Libanês Hospital, Adma Jafet 91, Bela Vista, SP, Zip Code 01308-050, Brazil. diogodtm@yahoo.com.br.
authors.forename: Diogo Torres
authors.initials: DT
authors.lastname: Marques
authors.forename: Regis Otaviano Franca
authors.initials: RO
authors.lastname: Bezerra
authors.forename: Luiz Tenório
authors.initials: LT
authors.lastname: de Brito Siqueira
authors.forename: Marcos Roberto
authors.initials: MR
authors.lastname: Menezes
authors.forename: Manoel
authors.initials: M
authors.lastname: de Souza Rocha
authors.forename: Giovanni Guido
authors.initials: GG
authors.lastname: Cerri