Fig. 2

Recurrent anaplastic astrocytoma, IDH-mutant. a) MRI showing initial tumor and 3 times recurrent tumors despite concurrent chemotherapy and radiotherapy. b) Initial tumor showing a sheet of neoplastic gemistocytic astrocytes with mild to moderate nuclear atypia, WHO grade III. c) The second recurrent tumor shows more pleomorphic nuclei with bizarre tumor cell features than those of initial tumor, but there is neither tumor necrosis nor microvascular proliferation. c, d) However, note IDH-1 and ATRX mutation were sustained (c: IDH1 (H09) staining, d: ATRX immunostaining)