Date Published:2015 Jan 12
A 13-year-old female presented with left unilateral proptosis, blurry vision, and diplopia. Clinical examination showed left sided visual acuity of 20/50, limited extraocular movement, 5-mm proptosis, and optic disc edema. CT and MRI displayed a large, intraconal, well-demarcated soft tissue mass with inferotemporal displacement of the optic nerve. The imaging appearance was unusual and diagnosis remained uncertain. Histopathologic analysis of the biopsy specimen confirmed the diagnosis of atypical syncytial meningioma. The tumor cells were positive for both androgen and progesterone receptors and the Ki67 stain was positive (proliferation index of 8%). The patient was treated with proton beam radiation therapy (total dose 50.4 GyE) that suppressed tumor growth and has preserved visual acuity to date (20/40). Differential diagnosis and approaches to therapy are explored.