Immunohistochemical studies of the tumor. (a-i) Magnification, ×200. The tumor cells expressed strong immunoreactivity for VIM (a) and negative for CK (b). Labeling index of Ki-67 (c) was 25%. MSA (d), SMA (e), DES (f) and S-100 protein (g) were negative in the tumor cells. (h) CD34 staining was detected in vascular endothelial cells rather than in tumor cells, highlighting the curvilinear capillaries. (i) MDM2 was positive in the tumor cells.