CD99 and neoplasm: On immunohistochemistry, the tumor cells had typically strong and diffuse positivity for vimentin and BCL2, focal positivity for CD34, and weak diffuse positivity for CD99 but negativity for cytokeratins AE1–AE3, actin HHF35, actin 1A4, calponin, caldesmon, desmin, S-100 protein, and collagen IV (Figures 9(c) and 9(d)).