The differential diagnosis between angiosarcoma and IPEH involves several key histologic features: (1) IPEH remains intravascular, whereas angiosarcomas invade surrounding tissue; (2) IPEH is often closely associated with a thrombus; (3) IPEH does not include necrotic tissue; and (4) IPEH has low mitotic activity [18, 19] and angiosarcomas are generally associated with high Ki-67 expression [22]. The gene discussed is MKI67; the disease is angiosarcoma.