Intravascular papillary endothelial hyperplasia of the extremities: MR imaging findings with pathologic correlation.

We report the MRI findings of three cases of intravascular papillary endothelial hyperplasia (IPEH) of the extremities with correlation of the pathologic findings. The IPEH is a non-neoplastic reactive lesion within the vessels and is commonly associated with thrombi. Signal intensity of the IPEH is complex due to the thrombi and the PEH itself. The thrombi are characterized by a slightly hyperintense signal on T1- and T2-weighted images compared with that of muscle when it comes at the medium stage of hemorrhage. Papillary endothelial hyperplastic tissue appears either as iso- or hyperintense to the muscle on T2- and T1-weighted images and shows variable enhancement on Gd-DTPA-enhanced images.