Figure 5. Microscopic examination showed a characteristic patternless pattern of spindle cells (A) with alternating hyper- and hypocellular areas (B), dense collagenous bands (C), staghorn vessels (D), and focal (<10%) tumor necrosis (E). On higher magnification (F), the cells exhibited bland, uniform, elongated nuclei with indistinct nucleoli, minimal atypia, and occasional (>4/10 HPF) mitotic figures. Immunohistochemical stains showed the tumor cells to be positive for CD34 (G), STAT6, TLE1, Desmin, AE1/AE3 (focal), CAM5.2 (focal), Beta-catenin and BCL-2, and negative for CD117, S100, Melan-A, SOX10, and ER. Ki-67 was positive in less than 1% of cells.