Fig. 2

Histopathological staining results of the tumor. The mass was composed of multiple nodules with well-defined borders and no membranes (Fig. a, 1×), and the mass was nondestructively mixed with adipose tissue (Fig. b, 10×). Some regions of the mass were composed of numerous capillaries filled with many red blood cells (Fig. c, 40×). The capillaries were lined with endothelial cells with round to oval nuclei, and the interstitial components were not clear. Collagen fibers were dissolved, and there was interstitial edema (Fig. d, 40×). The interstitium was significantly widened, and many filamentous collagen fibers, as well as proliferated capillaries, were observed, along with many neutrophils in some local areas (Fig. e, 40×). The proliferative capillaries exhibited good differentiation, with little cellular atypia and few mitotic figures. In some areas, the tumor was composed solely of spindle-shaped cells in the fibrous stroma, and groups of these spindle-shaped cells were mixed with microtubular structures (Fig. f, 40×)