Fig. 6

Histopathological features in the calcification group are shown. Patient 2 (a) had World Health Organization (WHO) grade 3 astrocytoma and was positive for isocitrate dehydrogenase 1 (IDH-1) R132H and O6-methylguanine DNA methyltransferase (MGMT) protein. Patient 11 (b) had WHO grade 4 glioblastoma and was negative for IDH-1 R132H and MGMT protein. Gadolinium contrast-enhanced (Gd-CE) T1 weighted imaging (T1WI) at the time of initial onset (upper), Gd-CE T1WI (middle row) and plain CT showing calcification (white arrows on CT, lower row) at the time of recurrence under bevacizumab (BVZ) treatment are also shown. The initial tumor tissue (upper row), core lesion (middle row), and calcification (lower row) of recurrent tumor tissue were compared with hematoxylin–eosin (H–E) staining and immunohistochemistry for CD34 and hypoxia-inducible factor 1α (HIF-1α). All scale bars, 100 μm.