Multiple lesions of intravascular papillary endothelial hyperplasia (Masson's lesions).

We recently encountered an elderly female patient with multiple, rapidly growing vascular lesions on her forearm. Histologic examination and immunoperoxidase studies were performed to identify cells present within the lesions. The growths proved to be intravascular papillary endothelial hyperplasia. Immunohistochemical studies showed these lesions to be proliferations of factor VIII+, factor XIIIa+, and CD34+ cells. Intravascular papillary endothelial hyperplasia lesions are growths that histologically can mimic angiosarcoma, especially when they are multiple. They appear to be proliferations of endothelial cells and also contain dermal dendrocytes. This finding raises the question as to the exact origin of the cells that give rise to these tumors.