Skip to content

Optic Pathway Glioma

Summary

  • Optic pathway gliomas (OPGs) are low-grade astrocytomas affecting the optic nerves, chiasm, and/or optic tracts
  • Commonly associated with neurofibromatosis type 1 (NF1)
  • Typically present in childhood with visual disturbances, proptosis, or endocrine dysfunction1

Pathophysiology

  • Arise from glial cells (primarily astrocytes) of the optic pathway
  • WHO grade 1 pilocytic astrocytomas in most cases
  • May involve:
    • Optic nerves
    • Optic chiasm
    • Optic tracts
    • Hypothalamus (in some cases)
  • Associated with NF1 mutations in about 30% of cases

Demographics

  • Most common in children, with 75% diagnosed before age 10
  • Accounts for 3-5% of all paediatric brain tumours
  • Slightly higher incidence in females
  • 15-20% of NF1 patients develop OPGs

Diagnosis

  • Clinical presentation:
    • Visual disturbances (decreased acuity, visual field defects)
    • Proptosis
    • Strabismus
    • Nystagmus
    • Endocrine dysfunction (if hypothalamic involvement)
  • Ophthalmologic examination:
    • Optic disc pallor or swelling
    • Visual field testing
  • Endocrine evaluation if hypothalamic involvement suspected

Imaging

  • MRI is the imaging modality of choice
    • T1-weighted: Iso- to hypointense
    • T2-weighted: Hyperintense
    • FLAIR: Hyperintense
    • T1 post-contrast: Variable enhancement patterns
  • CT:
    • Hypodense or isodense masses
    • Calcifications uncommon
  • Key imaging features:
    • Fusiform enlargement of optic nerves
    • "Dotted i" sign: chiasmatic involvement with posterior extension
    • Hypothalamic involvement may appear as a suprasellar mass

panels-1

  • A right sided orbital optic nerve glioma caused fusiform dilatation and hyperintensity of the optic nerve without enhancement.

Treatment

  • Often observed (especially NF1-associated, which are indolent); chemotherapy for progression, with surgery/radiotherapy reserved to preserve vision

Differential diagnosis

Imaging differential Differentiating feature
Craniopharyngioma Calcifications on imaging, suprasellar location
Meningioma Dural tail sign on MRI; peripheral "tram-track" pattern; intracranial extension along dura
Pituitary adenoma Sellar location; suprasellar extension compressing chiasm from below; no intrinsic nerve enlargement
Optic nerve sheath meningioma "Tram-track" enhancement on CT; nerve spared centrally; calcifications
Optic neuritis Enhancement of nerve without fusiform enlargement; no mass effect; resolves on follow-up
Multiple sclerosis Short T2 signal in optic nerve without mass effect; periventricular brain lesions; Dawson's fingers
Langerhans cell histiocytosis Lytic calvarial or orbital bone lesions; infundibular thickening; diabetes insipidus on MRI
Orbital lymphoma Homogeneous enhancing mass moulding around orbital structures; no tubular nerve enlargement

  1. Elzaafarany et al. Optic Pathway Glioma: Current Treatment Approaches and Ongoing Clinical Trials. 2025. Brain sciences - Open in new tab. ↩