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Optic Pathway Glioma


KEY FACTS

Terminology

  • Optic pathway glioma (OPG)

  • Primary neuroglial tumor of optic pathway

  • 3 broad clinical subtypes

    • Childhood syndromic [neurofibromatosis type 1 (NF1)], childhood sporadic, adult

Imaging

  • Fusiform optic nerve (ON) mass with variable posterior pathway involvement

  • MR is preferred imaging modality

    • Isointense to mildly hypointense on T1WI

    • Variably hyperintense on T2WI

    • Enhancement varies from none/minimal to intense

  • Associated neuroimaging findings in NF1: ↑ T2 foci in brain, other CNS tumors, sphenoid dysplasia, buphthalmos

Top Differential Diagnoses

  • Optic neuritis

  • ON sheath meningioma

  • Idiopathic orbital inflammatory pseudotumor

  • Sarcoidosis

Pathology

  • Childhood OPG: Low-grade glioma

  • Adult OPG: Anaplastic astrocytoma or glioblastoma multiforme

Clinical Issues

  • Decreased vision, proptosis; often asymptomatic

  • Childhood OPG: Onset 0.5-15 years

  • 30-40% of patients with OPG have NF1

  • 11-30% of patients with NF1 have OPG

  • Natural history highly variable

    • Generally indolent in childhood OPG

    • Much more aggressive in adults

      • –

        Poor prognosis; often rapidly fatal

Axial graphic depicts a left optic pathway glioma extending along the length of the intraorbital nerve, through the enlarged optic canal, and into the prechiasmatic segment. The fusiform pattern of enlargement is typical.

Clinical photograph of a child with a large optic nerve glioma shows striking proptosis
with bulging orbital contents, diplopia
.

(Top) Gross pathology of optic nerve glioma shows fusiform enlargement of the optic nerve
. (Bottom) Axial T2WI shows optic nerve glioma
with anterior displacement, compression of the globe
.

Axial T1C+ FS in another case of optic pathway glioma shows fusiform enlargement, enhancement of the prechiasmatic segment of the left optic nerve
, in addition to the marked enlargement and enhancement of the intraorbital optic nerve
.

TERMINOLOGY

Abbreviations

  • Optic pathway glioma (OPG)

Synonyms

  • Optic nerve glioma; anterior visual pathway glioma

Definitions

  • Primary neuroglial tumor of optic pathway

  • 3 broad subtypes

    • Childhood benign tumors: Associated with neurofibromatosis type 1( NF1 ), syndromic 30-40%

    • Childhood benign tumors: No NF1 association (sporadic)

    • Adult tumors: Typically malignant

IMAGING

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