Pediatr Surg Int (1995) 10:186-187 © Springer-Verlag 1995 A. K. Sharma • A. Wakhlu Retroperitoneal pseudocyst Accepted: 10 April 1994 Abstract There is a paucity of reports in the literature describing non-trau- matic retroperitoneal pseudocysts. We report a retroperitoneal pseudocyst in a young girl that developed within a short period of time for which no etiologic factor could be elicited on the basis of the clinical, investigative, operative or pathologic findings. Treatment was by primary complete excision. We propose that such pseu- docysts can form without preceding trauma. Key words Retroperitoneal pseudo- cyst • Pararenal pseudocyst Introduction A large number of reports in the literature describe pararenal pseudo- cysts that occur following the extra- vasation of urine or blood. These pseudocysts have specific etiologic, diagnostic, and pathologic features and require definite predisposing fac- tors for their formation. We report a child with a retroperitoneal pseudocyst without any of these features. No etiology could be determined for the A. K. Sharma • A. Wakhlu Department of Paediatric Surgery, SMS Medical College and Allied, SP Mother and Child Health Institute, Jaipur, India A. K. Sharma (~) B-2 Doctors Bungalow, Gangwal Park, Jaipur, India development of the pseudocyst, and in a review of the available literature we could not find any similar report. Case report A 3-year-old female presented with a mass in the left side of the abdomen noticed by the parents 10 days prior to admission. The child was otherwise asymptomatic. A history of any kind of trauma was categorically denied by the parents. Three months previously the child had been hospitalized with acute pain in the right side of the abdomen and had been fully investi- gated. At that time the laboratory tests, including serum amylase levels, and sonography of the abdomen were nor- mal. Clinical examination revealed a well-defined, nontender, irregular mass in the left lumbar region with restricted mobility. Laboratory tests including a hemogram, blood urea nitrogen, and creatinine levels were normal. Intravenous urography showed normal function in both kid- neys with slight medial displacement of the left ureter. There were no hydronephrotic changes. Sonography of the abdomen showed a multicystic left retroperitoneal mass with mixed echogenicity that displaced the left kidney upward (Fig. 1). On exploration, the 15x7x5-cm mass was found to consist of three thick-walled, non-communicat- ing cysts that contained clear fluid. Fig. 1 Sonogram showing multicystic retro- peritoneal mass anterior to left kidney The mass was situated anterior to the left kidney outside Gerota's fascia and was completely excised. The intra- operative impression was a retroperi- toneal cystic lymphangioma. Histo- pathologic examination of the mass showed the absence of an epithelial lining; the wall was composed of collagen and fibrin with inflamma- tory-cell infiltration. Biochemical analysis of the fluid was not done. These features were suggestive of a retroperitoneal pseudocyst. Discussion Juxtarenal collections of fluid or blood were classified by Spriggs into: (1) perirenal extravasation of urine; (2) perinephric hematomas; and (3) peri- nephric cysts of doubtful origin. These