Figure 1
Small cell variant of glioblastoma. H&E, OLIG2, and IDH1 stained sections from a case of small cell glioblastoma (a–c). As shown in H&E section (a), all cases of small cell glioblastoma showed small neoplastic astrocytic cells with uniform, bland oval nuclei and numerous mitotic figures (arrows in a). Chicken-wire vasculature and perinuclear halos were common histologic findings, as seen in this case (a), as well as microvascular proliferation (arrows in b). Ninety-eight percent of small cell glioblastomas demonstrated strong nuclear OLIG2 expression (b, Table 1), although OLIG2 expression was patchy to focal in 16% of cases (Table 1). All 45 cases were negative for R132H IDH1 mutant protein expression (c, Table 1).
