A healthy 17-year-old male presented with a 2-year history of progressive left upper eyelid ptosis. He denied pain, diplopia, and vision loss. Examination revealed normal visual acuity, intraocular pressure, pupillary response, color vision, and extraocular movement in OU. Hertel exophthalmometry demonstrated 1.5 mm of relative left-sided proptosis, and a margin reflex distance 1 of 1 mm was noted on the OS and 2.5 mm on the OD (Fig. 1A). Posterior segment exam was notable for left optic disc elevation without pallor or hemorrhage. MRI demonstrated a 2.7 × 2.2 × 1.8 cm intraconal mass encasing the optic nerve with enhancement extending into the optic canal and abutting the orbital apex with suggestion of superior orbital fissure and cavernous sinus involvement (Fig. 1B, C).FIG. 1Orbitotomy with biopsy was considered for definitive diagnosis, but given the lesion’s proximity to the optic apparatus and the high suspicion for optic nerve sheath meningioma, Gallium-68 DOTA-Tyr³-Octreotate (DOTATATE) positron emission tomography/CT was performed. DOTATATE is a radiolabeled somatostatin analog that binds to somatostatin receptor subtype 2, which is overexpressed in meningiomas, allowing for targeted imaging of these lesions. The scan revealed intense receptor avidity confined to the mass (Fig. 2) and, on a coronal slice through the optic canal, focal uptake along the intracanalicular segment of the optic nerve (arrow in Fig. 2), supporting a presumptive diagnosis of optic nerve sheath meningioma. There was no DOTATATE avidity across the superior orbital fissure or cavernous sinus despite MRI enhancement at these sites, suggesting reactive dural enhancement rather than true meningiomatous extension. The patient was initiated on fractionated stereotactic radiotherapy (54 Gy in 30 fractions). To our knowledge, this represents one of a handful of reported cases of optic nerve sheath meningioma diagnosed noninvasively using DOTATATE positron emission tomography/CT. This case highlights the utility of DOTATATE imaging in orbital tumor diagnosis and its potential to obviate biopsy when the lesion involves critical neurovascular structures.FIG. 2
Murdock et al. (2025) studied this question.