Intravascular papillary endothelial hyperplasia of the renal vein.

Intravascular papillary endothelial hyperplasia (IPEH) is a benign, florid proliferation of endothelial cells forming hyaline papillae covered by monolayered cells, which has rarely been described in the renal vein, most often being equated to tumors because of the difficulties in correctly interpreting imaging findings and accordingly treated by nephrectomy. If the kidney is end-staged for preexisting medical diseases, the risk of overtreatment is obviously negligible, but overdiagnosing IPEH as an intravascular tumor, either benign or malignant, may be perilous for the patient because of the possible consequences on the clinical management.