Figure 2.

(A) Brain tumor resection specimen from a patient with known metastatic breast carcinoma 6 months after Gamma knife SRS (20 Gy to 50% isodose line). The area of necrosis appears hypocellular and sharply demarcated from the surrounding gliotic brain. Few necrotic, hyalinized blood vessels (yellow arrows) are present, as well as scattered reactive astrocytes (green arrows). Overall features are those of a radiation necrosis. (B) Foamy macrophages are often present. The capillaries appear ectatic and congested. (C) Focal area shows increased cellularity with more nuclear pleomorphism in an otherwise hyalinised background, raising the possibility of residual viable tumor. (D) Immunostain (brown) with GATA3 labels numerous viable tumor cells. Nuclear pleomorphism appears more prominent and highlighted by this nuclear stain.