[Retroperitoneal cyst: a case report]

A 71-year-old woman who had an abdominal mass was admitted to our hospital in May, 1983. Physical examination revealed the presence of a soft mass without tenderness in the right upper abdomen. The results of laboratory tests were within the normal range. An excretory urogram showed a slight lateral displacement of the upper position of the right ureter and a slight dilatation of the right pyelocalyceal system. The urogram for the left kidney and ureter was normal. Abdominal CT scan revealed a cystic homogeneous mass anterior to the right kidney, 12 X 11 cm in size. Ultrasonography showed a cystic mass corresponding to the CT scan finding. Under ultrasonographic guidance, percutaneous puncture of the cyst was performed, and 800 ml clear straw-yellow fluid containing 457 ng/ml alpha-fetoprotein was drained. A repeat CT scan 9 months later showed no evidence of fluid reaccumulation and the patient remained asymptomatic.