Atypical acute presentation of an optic nerve sheath meningioma

PURPOSE: Primary optic nerve sheath meningiomas (ONSM) are benign lesions that typically present with findings of painless proptosis (59%), optic nerve pallor (55%), and decreased peripheral vision (35%). Herein we share an atypical case of a patient who presented acutely with periorbital pain and optic nerve head edema, and was ultimately determined to have a low-grade optic nerve meningioma. OBSERVATIONS: A 36-year-old healthy woman presented with acute onset of left periorbital discomfort. She was found to have intact visual acuity, full peripheral vision, and ipsilateral optic nerve edema. MRI imaging revealed a large intraconal mass partially encircling the left optic nerve. Incisional biopsy revealed a diagnosis of meningioma, WHO grade 1. CONCLUSIONS: Low-grade optic nerve sheath meningiomas may uncommonly present with acute pain and optic nerve head swelling, and absence of classic disease features.