OPTIC NERVE SHEATH MENINGIOMAS IN CHILDREN- DIAGNOSTIC CHALLENGES BASED ON A CASE SERIES

Abstract AIMS Optic nerve sheath meningiomas (ONSM) are rare, comprising 1-2% of paediatric CNS meningiomas. Due to this, no clear diagnostic consensus exists and much of management relies on case series. Their proximity to the optic nerve complicates biopsy. Our study focuses on diagnostic and therapeutic challenges when a pathological diagnosis is not feasible. METHODS We searched our Neuro-Oncology MDT database for patients treated for ONSM between January 2018-January 2024. We reviewed clinical presentation and diagnostic workup that led to the diagnosis. RESULTS 7 children aged 3-16years were identified over 5 years. Only 2/7 patients underwent a biopsy. Presenting symptoms included headache, acute vision loss and eye pain. 2/7 patients presented with bilateral symptoms of deteriorating vision. Average time between symptom onset and presentation was 8 months (3 to 15 months). Identified causes of delayed diagnosis included delayed presentation relating to COVID-19 pandemic (2 patients) and impaired imaging quality due to dental braces (1 patient). Whilst awaiting diagnosis, 3 patients had complete vision loss in their affected eye. Diagnostic workup included: optic disc examination (7 patients), lumbar puncture (2 patients), angiotensin-converting enzyme (2 patients), MRI brain and spine (7 patients), CT scan (5 patients), PET-DOTATE scan (3 patients), genetic testing for Neu- rofibromatosis Type 2 (4 patients). Regarding treatment, 1 patient had radiotherapy and 2 patients are having proton beam therapy. 1 patient underwent an enucleation, 1 excision of the affected optic nerve and 3 remain on surveillance. CONCLUSION Paediatric ONSM diagnosis remains challenging despite advanced imaging. We highlight the added value of CT and PET-DOTATATE when biopsy is high-risk. CT reveals calcification in 20-50% ONSM while PET-DOTATATE is related to the expression of somatostatin receptor 2 in meningiomas. Despite treatment, vision loss may occur, emphasising early multidisciplinary consultations for better outcomes.