Ga-68 DOTATATE PET/CT in a 19-Year-Old Male with Left Optic Nerve Sheath Meningioma: Diagnostic Utility in Differentiating Inflammatory Perineuritis

Abstract

Background: Optic nerve sheath meningioma is an uncommon tumour arising from the meningothelial cells of the optic nerve sheath. Diagnostic challenges can arise when differentiating optic nerve sheath meningioma and optic neuritis due to similar clinical presentation and magnetic resonance imaging findings. A delay in diagnosis can lead to a delay in appropriate therapy thereby increasing the risk of irreversible vision loss.

Case: A 19-year-old male presented with progressive, painless, unilateral (left) vision loss over one year. Initial MRI brain and orbits with gadolinium demonstrated increased T2 signal in the left optic nerve with the diagnostic impression being left optic neuritis. Initial laboratory testing excluded infectious and inflammatory aetiologies. Repeat MRI three months later demonstrated persistent enhancement of the left optic nerve. The possibility of optic nerve sheath meningioma was raised and therefore, a Ga-68 DOTATATE PET/CT was arranged. This demonstrated linear fusiform uptake (SUVmax 6.4) along the left optic nerve extending to the orbital apex, consistent with a somatostatin receptor expressing lesion such as an optic nerve sheath meningioma.

Conclusion: This case highlights the diagnostic value of Ga-68 DOTATATE PET/CT in confirming optic nerve sheath meningioma in young patients with atypical or equivocal MRI findings and negative inflammatory markers.