Figure 3.

Histopathologic correlation of recurrent glioblastoma tissue samples obtained from regions with and without reduced diffusion using image-guided stereotactic neurosurgical techniques in a patient demonstrating salt & pepper phenotype following bevacizumab therapy. (a) Intraoperative tissue sampling site superimposed on a post-therapeutic T1-weighted contrast-enhanced image, diffusion-weighted image, and apparent diffusion coefficient (ADC) map demonstrates mass like infiltrative T2 hyperintensity involving the left frontal lobe associated with salt & pepper phenotype reduced diffusion and minimal contrast enhancement. Tissue sampling site from region without reduced diffusion (left) demonstrated ADC_min of 842 and ADC_mean of 951. Tissue sampling site from region with reduced diffusion demonstrated ADC_min of 485 and ADC_mean of 646 (right). (b) Tissue samples obtained from region of recurrent tumor without reduced diffusion (blue region of interest [ROI]) demonstrated infiltrating cellular tumor (left; H&E stain 200× magnification), cellular proliferation of 1% (middle; Ki-67), with minimal vascular hyperplasia (right; factor VIII = delicate vascular appearance). (c) Tissue samples obtained from region of recurrent tumor with reduced diffusion (red ROI) demonstrated infiltrating cellular tumor (left; H&E stain 10× magnification) with elevated cellular proliferation (middle; Ki-67 = 11%), and predominantly simple vascular hyperplasia (right; factor VIII). No significant necrosis was observed within either tissue specimens. (Color version of figure is available online.)