Sonographic features of intravascular papillary endothelial hyperplasia (Masson's tumor) in the forearm.

Intravascular papillary endothelial hyperplasia, also known as Masson's tumor, is a benign, vascular lesion in which there is papillary proliferation of endothelial cells. The lesion presents as a palpable soft-tissue mass, often located within normal or dilated vascular spaces, and may be mistaken for a sarcomatous tumor on imaging. We present the case of an intravascular papillary endothelial hyperplasia in the forearm, with a remarkable appearance on color Doppler sonography, and suggest that this entity will be encountered more frequently by sonologists in the future.