Intravascular papillary endothelial hyperplasia (Masson's hemangioma) presenting as a lateral neck mass.

Intravascular papillary endothelial hyperplasia (Masson's hemangioma) is a benign disease of vascular origin characterized by exuberant endothelial proliferation in normal blood vessels.The most important feature of the disease is its resemblance to hemangiosarcoma and the resulting possible radiologic misinterpretation. We present the radiologic findings in a 45-year-old woman presenting a neck mass extending to the thoracic cavity.