Describe a case of bilateral synchronous orbital muscle infiltration of extraneural glioblastoma metastases

Glioblastomas are malignant, locally invasive primary brain tumors which rarely metastasize outside of the central nervous system. The paucity of extraneural metastases of malignant glioma remains a curiosity. One hypothesis is the relatively low level of driver mutations, when compared to hyper-mutated tumors such as melanoma and NSCLC, do not permit adaptation to systemic environs. Previous reports of extraneural metastasis in IDH wild-type, MGMT promoter un-methylated glioblastoma have observed a neoplastic clonal subpopulation of tumor cells responsible for glioblastoma metastasis. To our knowledge this is the first report of bilateral synchronous orbital muscle infiltration of extraneural glioblastoma.

CASE

A 60 year-old male with a history of multiply recurrent glioblastoma (IDH wild-type, MGMT promoter unmethylated) with disease initially present in the left temporal lobe, developed insidious bilateral ophthalmoparesis and ptosis with radiographic evidence of tumor infiltration of the bilateral extraocular muscles. At the time of malignant orbital extraocular muscle infiltration, the patient was on bevacizumab monotherapy. Given the patient’s good performance status (he continued to work full time) and the associated morbidity, he was treated with palliative radiotherapy to both orbits (30 Gy in five fractions) with symptomatic and radiographic improvement. Bevacizumab was continued through radiation and thereafter. Two months after RT he developed symptomatic perineural spread of tumor along the left V2 nerve and the masticator space manifesting predominantly as facial swelling. He elected to pursue hospice and passed two months later.

This patient’s case demonstrates that though metastasis of glioblastoma is rare, it is possible, and may be responsive to focal therapy.