A 37-year-old woman complained of left-sided painless vision loss and dyschromatopsia for several weeks. On examination, there was a decreased visual acuity on the left side. She was diagnosed with optic neuritis. However, during treatment with intravenous methylprednisolone, there was significant worsening of the visual acuity in one-month time.
An MRI of the brain was performed and showed fusiform swelling of the left optic nerve with high signal intensity on T2-weighted images and intense enhancement of the intraorbital and intracanalicular segments (figure 1A and B). In addition, the MRI showed a discrete focal hyperintensity on the T2-FLAIR images in the pons on the left side (Figure 1C), showing ring enhancement on the post-contrast images (Figure 1E). Additionally, two additional small punctiform enhancing lesions in the basal ganglia were observed, one on both sides (Figure 1G and H).
Despite all other negative tests, she was diagnosed with possible neurosarcoidosis and treated with cyclophosphamides. However, after 3 months, she was admitted to the neurology ward with severe neurological worsening and a control MRI of the brain was performed.
This follow-up MRI obtained 3 months later shows a distinct progressive disease with new expansive infiltrating lesions in the brain involving the right middle cerebellar peduncle, the pons (which is diffusely enlarged), the midbrain, the optic chiasm, the left hypothalamus, the left thalamus and the basal ganglia bilaterally (Figure 2A). On post-contrast images, these lesions show multiple areas of ring enhancement (Figure 2B). There is also a remarkable progressive thickening and enhancement of the left optic nerve (Figure 2B), with extension beyond the intracanalicular segment into the prechiasmatic segment and the optic chiasm.
A biopsy of the lesion in the left thalamus was performed and established the diagnosis of high-grade glioma, type glioblastoma (WHO type IV). The patient died within one year.
Optic nerve gliomas represent 2% of all brain tumours and are classified as low-grade gliomas of childhood and malignant high-grade gliomas of adulthood. Malignant glioma’s of the optic pathway, such as optic nerve or optic chiasm, is pathologically classified as either anaplastic astrocytoma (WHO grade III) or glioblastoma (WHO grade IV). They were first described by Hoyt in 1973  and are exceedingly rare. They occur mostly in the middle-aged man with a reported mean age of 54 years .
Initially, they are often misdiagnosed as optic neuritis and therefore treated with corticosteroids, usually with only a discrete or no response.
On MRI, in the early stages the imaging features are relatively non-specific and may mimic inflammatory disorders . Mostly, there is an expansile T2/FLAIR hyperintense appearance of the nerve suggestive of an infiltrative lesion . The tumour mostly enhances after administration of contrast, with sometimes a heterogeneous pattern of cystic/necrotic areas. As the tumour grows, there can be contiguous spread to the optic chiasm and tract, and even extension into the hypothalamus, basal ganglia and internal capsule can be seen . A multifocal or multicentric pattern is seen when there is multiple infiltrating T2 /FLAIR lesion in the brain, as seen in our case.
The diagnosis of malignant optic pathway glioma’s should be kept in mind in patients with lesions involving the optic nerves, the chiasm or optic pathways with additional infiltrating and aggressive lesions within the brain. An early diagnosis is important due to an otherwise rapidly fatal malignancy.
Written patient consent for this case not required
Patient data may have been modified to ensure patient anonymity.
 Sapna Rawal, Juan Pablo Cruz. Case of the week: glioblastoma involving the optic nerve. American Journal of Neuroradiology. October 2018
 Rahat Brar, Abhishek Prasad, Manpreet Brar. Glioblastoma of the optic pathways: An Atypical case. J Radiol Case Rep. 2009; 3(9): 22–28. (PMID: 22470685)
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.