Fig. 7

The histopathological findings and immunostaining. The tumor cells were composed of pleomorphic spindle cells and giant cells, and many typical and atypical mitotic figures were observed (a). On immunostaining, the tumor cells were focally positive for cluster of differentiation (CD) 117/KIT (b), α-smooth muscle actin (c), AE1/AE3 (d), and EMA (e) and negative for CD34 (f), DOG1 (g), h-caldesmon (h), desmin (i), S100 protein (j), and CD45 (k). Ki-67/MIB1 proliferation index was very high (l). (a ×100 magnification, b–l ×200 magnification)