Benign external compression of the inferior vena cava associated with thrombus formation.

Malignant and benign causes of inferior vena cava (IVC) occlusion and compression are recognized. Cases of benign IVC compression with associated distal thrombus formation have not however been frequently described. We present two cases of benign external IVC compression associated with distal thrombus formation; one resulting from a giant, benign, hepatic cyst, and another due to pelviureteric junction obstruction, resulting in massive hydronephrosis.