Optic pathway glioblastoma

Case contributed by Francis Deng
Diagnosis certain

Presentation

Painless loss of vision in the left eye. Over the course of 2 weeks, exam disclosed a left eye superior altitudinal visual field deficit progressing to no light perception, and right eye temporal field defect.

Patient Data

Age: 80 years
Gender: Male
ct
  • Thickening of the optic chiasm (axial, coronal, sagittal) and tracts

  • Small area of encephalomalacia in the left superior frontal gyrus

  • Left craniotomy for prior subdural hematoma evacuation

  • Generalized parenchymal volume loss

mri

FDG PET

Nuclear medicine

Hypermetabolism of the optic chiasm, prechiasmatic optic nerves, and postchiasmatic optic tracts, left greater than right, corresponding to the abnormality identified on prior MRI.

Case Discussion

The imaging findings were suggestive but not specific for a high grade glioma of the optic pathway. Differential considerations included lymphoma and metastases. Inflammatory disorders such as neuromyelitis optica were felt to be less likely given how expansile the lesion was.

A broad serum and CSF infectious and inflammatory workup was negative. CSF cytology was negative for malignant cells as well as IGH rearrangement and MYD88. Whole body PET, total spine MRI, and testicular ultrasound revealed no other sites of disease (not shown). The patient received empiric high dose steroids without improvement in vision but improvement of MRI findings. Empiric treatment for primary CNS lymphoma was undertaken consisting of palliative radiation and high dose methotrexate.

Following a decline in functional status and an episode of unresponsiveness concerning for seizure, biopsy was undertaken of the third ventricular lesion.

Pathology:

  • Integrated diagnosis: glioblastoma, CNS WHO grade 4

  • Histological diagnosis: anaplastic astrocytoma

  • Molecular information

    • IDH: negative (PCR)

    • ATRX: retained nuclear staining (immunohistochemistry)

    • p53: diffuse moderate positive staining (immunohistochemistry)

    • BRAF V600E: negative (immunohistochemistry; consistent with wild type)

    • H3K27M: negative (immunohistochemistry; consistent with wild type)

    • EGFR: amplified (FISH)

    • TERT promoter: mutant (Snapshot next-generation sequencing)

    • MGMT promoter methylation: positive

Glioblastoma of the optic chiasm is rare. Diagnosis is challenging due to inaccessibility for biopsy. The prognosis is poor. This patient died less than 4 months after initial presentation.

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