Vision loss in glioblastoma: Disease mimicking presumed therapeutic toxicity

Abstract

Glioblastoma is the most common and lethal form of primary brain cancer. In the recurrent setting, bevacizumab is a common choice for salvage therapy. Loss of vision in patients initially treated with radiation at the time of diagnosis and later treated with bevacizumab at time of recurrence has been reported, and presumed to be a treatment-related optic neuropathy. Strikingly, only 1 case report described a postmortem biopsy to rule out tumor involvement of the optic tracts. We report the first case of recurrent glioblastoma infiltrating the prechiasmatic and chiasmatic optic nerve, which at the time of vision loss was presumed to be secondary to bevacizumab. It is noteworthy that the MRI findings in the previously reported bevacizumab/radiation-induced optic neuropathy cases (without pathology follow-up) are comparable to our patient.

Keywords: Bevacizumab; Glioblastoma; Optic neuropathy; Radiation.

Fig. 1

Compound oblique sagittal T2/FLAIR (fluid-attenuated inversion recovery) reconstruction images through the right optic nerve: A) September 2015: Increased signal and mild swelling in the prechiasmtic right optic nerve. B) February 2016: Intraorbital increased signal in the right optic nerve now tracking into the optic chiasm (arrows). Also seen is increased T2 signal extending across the callosal splenium extending into the parietal and occipital lobes consistent with disease progression.

Fig. 2

Histology of the optic nerve from the patient’s postmortem biopsy. A) Whole mount section of optic chiasm stained with haemotoxylin & eosin (H&E) (upper panel A) and luxol fast blue with periodic acid-Shiff (LFB/PAS) (lower panel A). To the right there is loss of myelin staining secondary to tumor infiltration and necrosis. (Note: The line running through panel A in the H&E (upper) as well as the LFB/PAS (lower) represent a necessary cut in the photomicrograph order to encompass the entire nerve at low (2x) magnification; cuts were purposely made in different places. B) H&E stained section of the right side of the optic chiasm at original magnification of 20x. Infiltrating neoplastic astrocytes (arrows) and necrosis (*) have replaced myelinated axons of the optic nerve.