Glioblastoma multiforme of the optic chiasm: A rare case of common pathology

Abstract

Background: Malignant optic and chiasmatic gliomas are extremely rare, and are classified pathologically as anaplastic astrocytoma or glioblastoma multiforme (GBM). Approximately 40 cases of optic GBM in adults have been reported in the literature, and only five of them were described to originate from the optic chiasm.

Case description: An 82-year-old male patient with a past medical history of diabetes mellitus type 2, melanoma, and bladder cancer presented with gradual vision loss of the left eye in a period of 1 month. After neuro-ophthalmological examination, the decision of thither magnetic resonance imaging (MRI) studies was made. It showed a contrast enhancing mass in the region of the optic chiasm. In this case, imaging study was not enough to establish an accurate diagnosis and a left pterional craniotomy for biopsy and resection of the optic chiasmal mass was performed. After histological evaluation of the mass tissue, the diagnosis of GBM was made. Taking into account the patient's poor condition and unfavorable prognosis he was moved to inpatient hospice. The patient deceased within 2 months after surgery.

Conclusion: Chiasmal GBM is an extremely rare condition where a biopsy is necessary for accurate diagnosis and optimal treatment. Differential diagnosis for such lesions can be very difficult and include demyelinating optic neuritis and non-demyelinating inflammatory optic neuropathy (e.g., sarcoid), vascular lesions (e.g., cavernoma), compressive lesions of the optic apparatus, metastatic malignancy, and primary tumors of the anterior optic pathway. The role of chemotherapy and radiotherapy including novel stereotaxic radiosurgery methods is still unclear and will need to be evaluated.

Keywords: Brain tumor; glioblastoma; glioma.

Figure 1

Preoperative magnetic resonance imaging: Axial T1-weighted image with contrast demonstrating an enhancing lesion of the left pre-chiasmatic optic nerve and chiasm

Figure 2

A highly cellular astrocytic tumor is seen with marked microvascular proliferation (a), mitotic activity (b) and areas of necrosis (c). The tumor was strongly immunoreactive to glial fibrillary acidic protein immunohistochemistry (d) and the tumor nuclei were positive for p53 (e). The ki-67 proliferation index was estimated to be approximately 10% (f)