CR2 and glioblastoma: Negative EMA, CD34, SSTR2, and PR to exclude the possibility of most epithelial tumors and meningiomas; negative Langerin to exclude Langerhans cell-associated histiocytosis; negative CD21 to exclude out follicular dendritic cell sarcoma; negative GFAP and Oligo-2 to exclude glial tumors, such as glioblastoma and pleomorphic xanthoastrocytoma.