Fluorescence-Guided Operation in Recurrent Glioblastoma Multiforme Treated with Bevacizumab—Fluorescence of the Noncontrast Enhancing Tumor Tissue?

The oral application of 5-aminolevulinic acid (ALA) leads to an accumulation of fluorescent porphyrins in malignant glioma tissue, which simplifies complete tumor resection. If pretreated with bevacizumab, a vascular endothelial growth factor (VEGF) antibody, these patients might not show a contrast enhancement on magnetic resonance imaging (MRI) despite tumor progression. As VEGF antibodies induce a normalization of the tumor vasculature, it is not known whether fluorescence-guided surgery is of any value in patients pretreated with this antibody. One might speculate that missing contrast enhancement on MRI could result in minor or missing fluorescence after the application of ALA. Attempting to give some answers, we report the case of a patient who underwent fluorescence-guided reoperation of recurrent glioblastoma multiforme pretreated with bevacizumab.