Microscopic findings. (A) The tumor shows satellite or spindle cells with a myxoid stroma and medium-sized prominent vessels (hematoxylin and eosin stain, ×100). (B) The tumor shows medium-sized vessels with perivascular hyalinization and thickened walls (hematoxylin and eosin stain, ×200). (C) A few tumor cells reveal positive reactivity for smooth muscle actin (SMA) immunohistochemical staining (arrows, SMA, ×400). (D) The satellite tumor cells reveal negative reactivity for S-100 protein immunohistochemical staining (S-100, ×400).