An Atypical Paediatric Optic Nerve Sheath Meningioma.

A 16-year-old male presented with a three year history of right proptosis. All other ocular findings were normal. Imaging demonstrated a large, calcified, contrast-enhancing mass in the apical orbit. The tumour had high gallium-68-DOTATATE uptake and low 18F-2-fluoro-2-deoxy-D-glucose uptake. An incisional biopsy revealed a diagnosis of psammomatous optic nerve sheath meningioma (ONSM). One year later stereotactic radiotherapy was performed due to tumour growth. Tumour size and visual acuity remained stable in the six months after treatment. This case differs from previously reported paediatric ONSMs by its histo-clinical characteristics (exophytic-calcified mass, visual preservation, psammomatous histology).