Retroperitoneal multiple lymphangioma with differential cyst contents causing hydronephrosis and biliary dilatation.

We report a 40-year-old woman with retroperitoneal multiple cystic lymphangioma. Multiple cystic lesions were found on both sides of the aorta in the retroperitoneal and right pelvic spaces. These thin-walled cysts gradually increased in size leading to left hydronephrosis and dilatation of the common bile duct with cholecystitis, requiring resection. Analysis of cystic contents revealed differences between the cysts. The right cyst contained high concentrations of amylase, 3429 U/L, while the left cyst contained high concentrations of triglyceride, 470 mg/dL. No reports of patients with idiopathic retroperitoneal cystic lymphangioma have described differences in cystic contents. Differences in cystic contents according to tumor location strongly suggest that the cause of retroperitoneal lymphangioma is a developmental malformation in which lymphangiectasia follows the failure of developing lymphatic tissue to establish normal communication with the remainder of the lymphatic system.