Renal peripelvic lymphangiectasia after bilateral renal vein thrombosis.

Renal peripelvic lymphangiectasia (RPL) is one of the rare conditions that mimic renal cysts. Its physiopathology remains unknown, but an association with renal vein thrombosis has been reported. We share the case of a male patient in his 20s suffering from antiphosphlipid syndrome. The patient was hospitalised for thrombosis of the inferior vena cava (IVC) extending from the iliac veins to the level of renal veins. Consecutive CT and clinical follow-up over the course of 14 years showed the development of numerous retroperitoneal venous collaterals and the apparition of several bilateral peripelvic cystic lesions after extensive thrombosis of the IVC and both renal veins. The renal function remained normal throughout the follow-up. We suggest that the development of RPL is secondary to bilateral renal vein thrombosis. The presumed mechanism would be an increased hydrostatic pressure in the kidney capillaries leading to a more important interstitial fluid drainage by the lymphatic system. To our knowledge, this is the first well-documented case of renal vein thrombosis followed by RPL, contrasting with the previous hypothesis that compression by the lymphangiectasia could cause the thrombosis.